Role of Transesophageal Echocardiography in Surgical Treatment of Aortic Dissection

Abstract

Acute type A aortic dissection is a life-threatening condition frequently complicated by rupture and/or malperfusion, which can occur at any time. While computed tomography (CT) is the gold standard for preoperative diagnostic imaging to develop the optimal surgical strategy, transesophageal echocardiography (TEE) is invaluable in the operating room. TEE compensates for the limitations of CT by providing real-time information, enabling timely and accurate management of unexpected events such as rupture, perfusion-related dissection, or new malperfusion in the coronary, cerebral, and visceral arteries. These critical events, often occurring out of sight of the surgical field, can go unrecognized by surgeons, anesthesiologists, or perfusionists. TEE acts as a navigational radar in an airport control tower, guiding experienced pilots through complex situations. However, the effectiveness of TEE depends on the operator’s ability to use it at the optimal timing and target the correct anatomical structures. This chapter aims to elucidate the methodology, timing, and specific assessments required for TEE to optimize intraoperative management of aortic dissection, ensuring the best possible outcomes for patients.

1. Introduction

Acute type A aortic dissection (ATAAD) is often complicated by rupture and/or malperfusion, significantly worsening the prognosis of patients. According to the “Annual Report” published annually by the Japanese Association for Thoracic Surgery, the operative mortality of ATAAD was as high as 18.4% in 2000. However, by 2020, this figure had decreased to 5.7% [1]. This improvement is attributed to advancements in computed tomography (CT)—the gold standard for diagnostic imaging—refinements in surgical strategies, and the development of endovascular interventions [2]. The advent of 320-row CT has revolutionized diagnostic imaging by enabling the acquisition of whole-body images within seconds. It allows for the visualization of any plane, the creation of three-dimensional images, and the extraction of particular structures such as the aorta. These capabilities facilitate surgical planning based on objective, technologist-independent information, thereby improving surgical outcomes. However, there are situations where CT may not provide sufficient information for strategy formulation, particularly in cases of unstable hemodynamics due to shock or cardiac arrest, or when only limited images from preceding institutions are available. Furthermore, the definitive limitation of CT is that it becomes impractical once surgical treatment has commenced.

Transesophageal echocardiography (TEE) can compensate for this limitation. TEE provides not only morphological and kinetic information but also real-time hemodynamic data without radiation exposure or the need for contrast agents. The surgical strategies can be refined based on TEE-derived information [3]. However, the quality of TEE assessment can vary significantly among examiners. To address this variation, this chapter summarizes the standardized role of TEE in the management of ATAAD.

2. Flow of TEE assessment in the perioperative period

Figure 1 illustrates the flow of TEE assessment in the perioperative period. Initially, the surgeon formulates surgical and extracorporeal circulation (ECC) strategies based on CT-derived information. Incorporating additional data obtained from TEE—such as entry position, presence of bleeding, aortic regurgitation (AR), and malperfusion—the surgeon then finalizes the surgical plan. TEE-derived information is invaluable not only for strategy formulation but also for intraoperative assessment in the event of unexpected complications such as rupture or new malperfusion. Although such incidents are rare, data acquisition becomes extremely challenging once they occur. Therefore, it is advisable to complete a comprehensive TEE assessment beforehand. Given the unpredictability of such events, the author typically completes this assessment as quickly as possible, usually within 10 minutes.

Figure 1.

Time Course of Assessments and Consequential Processes or Procedures. CT: computed tomography, ECC: extracorporeal circulation, ICU: intensive care unit.

Various events can occur in the perioperative period. One common event is sudden hypotension before ECC is established, often caused by vasodilation due to anesthesia induction, but it can also result from myocardial ischemia, rupture, or dissection extension to the subclavian artery, all of which should be evaluated by TEE. Another critical event is the development of a new dissection or false lumen perfusion at the initiation of ECC. New complications can also arise after weaning from ECC, as illustrated by two cases later in this chapter. In the postoperative intensive care unit, pericardial tamponade or new malperfusion events may occur. In each scenario, a definitive “0 or 1” judgment is required. Even with extensive experience, decisions based on probability are not reliable; thus, TEE is employed to make definitive “0 or 1” decisions.

3. Intraoperative hypotension and ECC management

In cases of unexpected hypotension or an unusual decrease in the ECC system’s reservoir level, probable bleeding should be investigated. Before sternotomy, the free spaces, including the pericardial and pleural cavities, should be examined (Figure 2a). These areas can be assessed within seconds by rotating the TEE probe 90–120 degrees to the left and right.

Figure 2.

Findings of Rupture in Acute Type A Aortic Dissection. a: Quick assessment of rupture. b: Pericardial tamponade just before skin incision. c: Left pleural bleeding, with the bleeding point identified by TEE as an echo-free space. d: Rupture to the mediastinum, presenting with to-and-fro flow to the aorta. DAO: descending aorta, LV: left ventricle, RV: right ventricle.

Figure 2b depicts TEE images of a case where the patient’s blood pressure suddenly dropped to 30 mmHg before the skin incision. The TEE image revealed marked pericardial tamponade, prompting an urgent sternotomy. Although the heart was fibrillating on pericardiotomy, ECC was initiated while the heart was massaged. The surgical treatment proceeded as planned, and the patient was discharged without complications.

Figure 2c presents the CT and TEE findings of an 86-year-old female patient transferred in shock, associated with a left hemothorax [4]. CT was performed after draining 500 mL of blood, but neither the cause nor the bleeding site was identified. Due to recurrent shock, the patient underwent emergency open surgery. TEE revealed a type B aortic dissection and an echo-free space in the mediastinum adjacent to the aorta, indicating the bleeding site. Only 10 cm of the corresponding aorta was replaced. Although stent grafting might be an option, the bleeding site might not be located via aortography, necessitating broad stent graft placement, potentially leading to paraplegia. TEE aids in minimizing the length of coverage. In another case, a 58-year-old male patient (Figure 2d) presented with shock following mediastinal bleeding. TEE showed a to-and-fro flow between the mediastinum and the aorta, with the entry site 3 cm distal to it. Due to the rupture site’s proximity to the diaphragm and unknown Adamkiewicz artery level, only the minimal aorta segment including the rupture site was replaced to prevent paraplegia. Both patients had uneventful postoperative courses.

4. Identifying the entry site in aortic dissection with TEE

It is not uncommon for the entry site of an aortic dissection to be unidentified on CT images. In such cases, TEE can be employed to locate the entry site. The characteristic TEE finding for an entry site is an “interrupted intimal flap with blood flow through it.” However, visualizing the distal portion of the ascending aorta or the infrarenal portion of the abdominal aorta can be challenging. When the entry site is not visible, it is advisable to assess the direction of blood flow in the false lumen of the aortic arch. The location of the entry site can be inferred based on the direction of this flow. If the blood flow in the false lumen is antegrade, the entry site is likely in the ascending aorta (Figure 3a). Conversely, if the flow is retrograde, the entry site is likely in the distal portion of the aorta (Figure 3b). This approach can help pinpoint the entry site more accurately and assist in the formulation of appropriate surgical strategies.

Figure 3.

Locating Entry Site by TEE Findings. a: An entry in the ascending aorta (AAO) generating antegrade flow in the false lumen (FL) of the aortic arch. b: An entry in the descending aorta (DAO) causing retrograde flow in the FL of the aortic arch. TL: true lumen.

5. Aortic regurgitation

Acute aortic regurgitation caused by ATAAD significantly burdens the heart, often leading to pulmonary edema even in young patients before they can be taken to the operating room. There are three primary mechanisms of AR in this context (Figure 4a) [5].

1. Tethering of commissures: This occurs due to the enlargement of the ascending aorta and the sinotubular junction, preventing the cusps from coapting at the center. This results in a triangular regurgitant orifice and a central regurgitant jet (Figure 4b).

2. Prolapse of cusps: Prolapse occurs when the suspension of the commissures is lost due to the dissection of the aortic wall, leading to an eccentric regurgitant jet (Figure 4c).

3. Intimo-intimal intussusception: Rarely, a highly mobile intimal flap in the ascending aorta results in intimo-intimal intussusception or invagination into the aortic valve [6, 7, 8, 9, 10]. If there is a tear on the invaginated flap, regurgitation ensues (Figure 4d). This type of AR can also be associated with myocardial ischemia [6].

Figure 4.

Mechanisms of Aortic Regurgitation. a: Three types of mechanisms. b: Enlargement of the ascending aorta and sinotubular junction (STJ) causing tethering of commissures, forming a triangular regurgitant orifice. c: Dissection of the Valsalva sinus wall loosening the suspension of commissures, leading to cusp prolapse. d: Highly mobile flap with tear invaginating into the aortic valve causing incompetent valve closure.

Even moderate-to-severe AR may be addressed with repair rather than valve replacement. Repair strategies include resolving tethering by normalizing the size of the sinotubular junction during stump reconstruction or correcting the prolapse of the cusps by suspending the commissure to the reconstructed aortic wall.

6. Malperfusion

In ATAAD, any branch artery can be compromised by malperfusion. However, TEE primarily assesses the coronary arteries, arch branch arteries, and visceral arteries. The mechanism of malperfusion involves the “compressed true lumen by an expanded false lumen,” influenced by the entry blood flow and the presence of reentry (Figure 5a). There are two types of branch occlusion: aortic type and branch type (Figure 5b). In the aortic type, the intimal flap is pressed against the opposite wall, obstructing the branch orifice. This mechanism also affects the flap in the proximal aorta, reducing blood flow in the true lumen. In the branch type, the dissection extends into the branch artery, where the expanded false lumen compresses the true lumen. While the mechanisms are similar, the site of obstruction differs.

Figure 5.

Mechanisms, Types, and Assessment of Malperfusion. a: Absence of reentry and predominant flow into the false lumen (FL) causing malperfusion. b: Two types of malperfusion: aortic type and branch type, differentiated by TEE findings. c: Four zones to assess perfusion and specific modalities for each organ. ECG: electrocardiogram, NIRS: near-infrared spectroscopy, rSO2: regional oxygen saturation, SMA: superior mesenteric artery, TEE: transesophageal echocardiography.

TEE findings indicative of malperfusion include (1) a true lumen smaller than the false lumen and (2) no flow in the false lumen.

Detectable blood flow in the false lumen suggests the presence of a distal reentry, indicating that the target organ is perfused from either lumen and is not malperfused. In the superior mesenteric artery (SMA), significant malperfusion occurs when the true lumen is smaller than half of the entire lumen, likely because branch arteries from the SMA become obstructed, similar to the aorta. New malperfusion can arise at the initiation of ECC due to altered pressure gradients between the lumina. TEE’s role is to detect these changes. While CT visualizes the entire pathway from the aorta to the target organ, TEE has a limited visualization area. Therefore, intraoperative assessment of perfusion status integrates TEE with other modalities to evaluate perfu sion at four zones: (1) Aortic zone; (2) Branch zone; (3) Peripheral zone; and (4) Tissue zone (Figure 5c).

As illustrated in this figure, the majority of the assessment is performed using TEE.

6.1 Malperfusion of coronary arteries

Malperfusion of the coronary arteries is initially assessed by examining ventricular contraction (tissue zone) and subsequently by detailed examination of each coronary artery. Unlike typical myocardial infarction, where obstruction occurs within the coronary arteries, in ATAAD, obstruction typically occurs at the orifice and proximal portions of the coronary arteries (aortic and branch zones), making TEE assessment feasible. Figure 6a schematically illustrates the types of coronary artery malperfusion. The horizontal row depicts the morphological changes in the coronary artery and intima, while the vertical column shows the degree of dissection extension and the presence or absence of ischemia. When an entry tear is located in the ascending aorta, dissection rarely extends into the coronary artery, typically remaining at the orifice due to similar pressures in the true and false lumina. Conversely, if the entry is distal to the aortic arch, the false lumen pressure increases, exceeding the true lumen pressure, potentially leading to coronary artery dissection or orifice occlusion.

Figure 6.

Coronary Malperfusion. a: Types of dissection and occurrence of malperfusion. b: Findings in the left coronary artery (LCA). c: Findings in the right coronary artery (RCA). FL: false lumen, LAD: left anterior descending artery, LCX: left circumflex artery, LMT: left main truncus, RCS: right coronary sinus, TL: true lumen.

Figure 6b presents examples of left coronary artery dissection. In most cases, the left coronary artery remains intact (left), but occasionally it is occluded at the orifice (center), necessitating prompt perfusion restoration. If a flow signal is detectable in the false lumen, distal perfusion is maintained (right). However, branch-type dissections, shown in the lower row, may lead to subsequent malperfusion onset.

Figure 6c illustrates right coronary artery dissection. Typically, the dissection extends beyond the sinotubular junction but stops at the orifice. Due to the right coronary artery’s small diameter and its location on the outer curvature of the ascending aorta, dissection rarely extends into the artery, although the intima may be avulsed at the orifice. In such cases, the coronary artery is perfused via the false lumen, complicating cardioplegic solution infusion post-aortotomy. Hence, revascularization of the right coronary artery before aortotomy is advisable. This crucial information should be communicated to the surgeon. The rightmost figure shows an aortic-type occlusion of the right coronary artery. Impaired perfusion in this scenario must be conveyed to the surgical team.

There are reports suggesting that 3D-TEE is useful for coronary artery assessment [11, 12]. However, the author prefers using 2D and xPlane modes, employing 3D imaging only for understanding the spatial relationship of the coronary arteries.

6.2 Malperfusion of arch branch arteries

The treatment strategies for cases with occluded arch vessels remain controversial. Direct cannulation and perfusion to the occluded right common carotid artery have been attempted with fairly good results, as evidenced by meta-analyses [13, 14, 15, 16]. However, occlusion of the right common carotid artery does not necessarily result in cerebral ischemia. Cerebral perfusion is supplied by the bilateral internal carotid and vertebral arteries, which converge to form the basilar artery, and subsequently the circle of Willis. This compensatory system can offset the occlusion of a single vessel. Nonetheless, this system may not provide sufficient blood supply under the conditions of pulseless perfusion with relatively low perfusion pressure during ECC.

To address this challenge, the author has developed a three-stage monitoring protocol for cerebral perfusion (Figure 7a) [17]. Near-infrared spectroscopy (NIRS) is used for continuous monitoring of regional oxygen saturation in the bilateral frontal lobes (rSO₂), indicating perfusion from the carotid artery system (tissue zone). If rSO₂ levels drop below 55–60% [18] or if inadequate perfusion of the carotid artery system is suspected, orbital Doppler is employed (peripheral zone). The orbital Doppler technique involves placing a linear probe on the eyelid and visualizing the eye horizontally in a slightly inward direction. With the fundus at the 6-o’clock position, the blood flow signal in the optic nerve (central retinal artery) can be detected. The velocity range below 10 cm/sec is suitable for this purpose. Pulsed-wave Doppler provides information on pulsatility and velocity [19]. Detectable flow signal in the central retinal artery, despite occlusion of the ipsilateral carotid artery, indicates effective collateral circulation via the circle of Willis [20]. The ophthalmic artery, originating from the internal carotid artery, reflects perfusion in the carotid artery system. This artery can usually be detected even at perfusion pressures as low as 30 mmHg. A sustained absence of detectable flow in the ophthalmic artery is associated with cerebral infarction, while a lack of flow in the central retinal artery is linked to higher brain dysfunction such as delirium [21]. Orbital Doppler scanning should be completed within 10 seconds under hypothermia to avoid potential heat injury to the cornea. If cerebral malperfusion is suspected based on orbital Doppler findings, perfusion in the upstream branch arteries is examined using TEE (branch zone). One example is the malposition of a cannula for selective cerebral perfusion [22]. Although visualizing arch branch arteries with TEE can be challenging due to interference from the trachea, techniques such as using a fluid-filled balloon placed in the trachea have been reported [23]. However, most of these arteries can be visualized by lateral bending of the TEE probe and scanning from the side of the trachea [24]. Despite the need for specific manipulation techniques and anatomical knowledge, TEE provides valuable information on cerebral perfusion, particularly in treating ATAAD. In cases with an entry tear in the ascending aorta, the dissection often extends to the innominate artery, occasionally causing significant stenosis. Artificial perfusion from the right axillary artery typically recanalizes the innominate artery, although not always [25]. Real-time information on perfusion status is critical for this assessment. Figure 7b shows a balloon-like flap in the innominate artery with pulsatile to-and-fro movement. During systole, blood narrowly passes around it to perfuse the distal region, a finding not detectable by CT. Figure 7c illustrates the branch-type occlusion of the innominate artery, where antegrade flow in the right subclavian and right internal thoracic artery is present, but flow in the right vertebral artery is retrograde, indicating “subclavian steal” syndrome. Following aortic repair, all flows became antegrade. Figure 7d shows changes in the right common carotid artery; while it was patent before ECC, the true lumen collapsed post-ECC, likely due to dissection extension from the anastomosis site. Although this information covers limited areas, integrating these small data points provides a comprehensive understanding of the perfusion status.

Figure 7.

Cerebral Malperfusion. a: Cerebral perfusion system, normal and malperfused, and three-stage monitoring. b: Balloon-like flap in the innominate artery (IA) with to-and-fro movement. c: Narrowed true lumen (TL) in the IA leading to subclavian steal. d: New dissection in the right common carotid artery (RCCA) after extracorporeal circulation (ECC). AO: ascending aorta, ACA: anterior cerebral artery, FL false lumen, LCCA: left common carotid artery, LSCA: left subclavian artery, LVA: left vertebral artery, MCA: middle cerebral artery, NIRS: near-infrared spectroscopy, PCA: posterior cerebral artery, RCCA: right common carotid artery, RITA: right internal thoracic artery, RSCA: right subclavian artery, rSO2: regional oxygen saturation, RVA: right vertebral artery.

6.3 Malperfusion of visceral arteries

Mesenteric ischemia remains a challenging problem, often characterized by difficult diagnosis and the need for timely treatment [26, 27]. Real-time information obtained at the bedside is crucial for addressing this issue, which prompted the author to develop TEE visualization techniques for assessing visceral arteries (Figure 8a aorta and branch zone) [28].

Figure 8.

Visceral Malperfusion. a: TEE visualization of visceral arteries, scanned from the stomach posteriorly in the horizontal or sagittal plane. b: Aortic type malperfusion of superior mesenteric artery (SMA), with patent celiac artery (CEA). c: Occlusion of both arteries. d: Branch type malperfusion of SMA with compressed true lumen (TL). e: Intestinal ischemia presenting with dilatation, edematous wall and folds, and ascites. ABA: abdominal aorta, FL: faluse lumen, IVC: inferior vena cava, LRA: left renal artery, LRV: left renal vein, RRA: right renal artery.

To visualize these arteries, the TEE probe is advanced with the short-axis view of the descending aorta in sight. As the probe progresses, the vertebra, initially at the 4-o’clock position, moves to the 6-o’clock position around the level of the esophageal hiatus (TH10). The celiac artery appears at about 2 inches below (TH12), followed by the superior mesenteric artery (SMA) 1 inch further down (L1), and finally the renal arteries at L2 (Figure 8a). Scanning at a 90-degree plane provides a sagittal section of these arteries. The celiac artery branches perpendicularly from the anterior wall of the aorta and quickly divides into three arteries, while the SMA courses dorsally along the aorta. Although maintaining the image of the aorta on the screen requires upper and lateral bending of the probe, this technique yields valuable information on visceral perfusion [29, 30, 31].

Figure 8b depicts an aortic-type occlusion of the SMA with a patent celiac artery, while Figure 8c shows both arteries occluded, suggesting potential hepatic ischemia. Figure 8d illustrates a branch-type malperfusion with a flow signal only in the narrow true lumen. In all these cases, the intestine was necrotic. Given that the intestine is a muscular organ, malperfusion can be suspected by observing its morphology and kinetics (tissue zone). Figure 8e (left) shows ischemic intestines with a dilated lumen, thick edematous walls, and reduced peristalsis. Immediate evaluation of the SMA is critical because the window for salvaging the intestine is only about 4 hours. The right image shows a typical finding of a necrotic intestine with markedly dilated loops and visible Kerckring’s folds in the presence of abundant ascites, indicating the need for immediate laparotomy and resection.

These findings can also be obtained using surface ultrasonography. It is essential to utilize every available modality to gather comprehensive information and accurately assess the situation.

7. Initiation of ECC

ECC-induced dissection is rare, with an incidence of less than 0.3%, but its mortality is notably high, ranging from 20–48% [32, 33]. While ultrasound technologies can aid in rescuing patients [34], timely assessment is crucial. The author has encountered two such cases, both of whom were successfully rescued likely because the dissections were immediately detected with TEE and promptly treated. In the first case, aortic arch dissection occurred following perfusion from the right axillary artery. TEE revealed a linear image passing through the arch (Figure 9a) [35]. Despite the immediate cessation of the pump, the dissection had already extended to the descending aorta, reducing the true lumen to a slit-like structure. There was no unusual increase in perfusion pressure. In the second case, dissection appeared in the descending aorta approximately 10 seconds after initiating femoral arterial perfusion. TEE visualized the gradual prominence of a very thin intima at the 8–12 o’clock position, with slightly echogenic fine dots in the false lumen, which eventually occupied the entire aortic lumen (Figure 9b) [36]. In both cases, perfusion was redirected through an alternative route, perfusion in the individual branch arteries was checked, and the aorta was repaired. Both patients were discharged without significant sequelae.

Figure 9.

Events at the Initiation of Artificial Perfusion. a: Perfusion-induced dissection in the arch, with the intimal flap passing. b: New dissection in the descending aorta (DAO) with a very thin flap. c: Mechanism of false lumen (FL) perfusion. d: FL perfusion detected in DAO. e: FL perfusion detected in ascending aorta (AAO), with perfusion to the left coronary artery (LCA) detectable. RCA: right coronary artery, TL: true lumen.

If these occurrences had not been recognized, aortic-type malperfusion could have led to multiple organ failure, potentially being diagnosed as “stroke or hepatic failure of unknown reason.” The need for TEE assessment is apparent by the fact that no one else had recognized these events. TEE is only useful if employed at the right time and for the appropriate assessment. Importantly, dissection is difficult to recognize on TEE images after it has passed, but capturing the decisive moment is critical. Monitoring the downstream area of perfusion with TEE is essential.

Another significant event at this stage is false lumen perfusion, where perfused blood predominantly enters the false lumen through a reentry, causing aortic-type malperfusion due to increased pressure in the false lumen. Although there is an ongoing debate about the best perfusion strategy to prevent false lumen perfusion [37, 38, 39, 40], the author believes there is no single “best” strategy as situations vary in individual cases. The optimal approach is to “perfuse first and modify it as needed according to the result” [41]. To ascertain the “result” of initial perfusion, it is necessary to monitor the downstream area with TEE (Figure 9c).

This issue tends to occur in cases of retrograde type A dissection with the entry point in the abdominal aorta. Figure 9d illustrates changes in the descending aorta in one such case. The patient’s blood pressure suddenly dropped, and TEE clarified the reason. Before femoral arterial perfusion, blood flow was present only in the true lumen with spontaneous echo contrast (SEC) in the false lumen. Upon initiating perfusion, the true lumen collapsed, and the SEC in the false lumen moved upward and disappeared. Systemic perfusion was established via the left subclavian artery, and the scheduled repair was completed. Figure 9e shows TEE findings in the ascending aorta, which was filled with SEC following systemic perfusion, without any changes in other monitors. This indicated an enlarged false lumen. As coronary perfusion was maintained through the gap around the thin flap and there was no decrease in rSO₂, cooling continued and aortic replacement was performed. Both cases had uneventful postoperative courses without complications.

Recently, cannulation to the dissected arch has been reported [42, 43, 44, 45]. The author used this technique in one ECC-induced dissection case, and TEE was instrumental in detecting erroneous entry of the guidewire into the false lumen or unintendedly deep placement.

8. After weaning from ECC

Two cases of unexpected events after ECC are presented. In one case (Figure 10a), the patient experienced a sudden drop in blood pressure just before chest closure, despite an otherwise uneventful course [46]. TEE revealed dyskinesia in the anterior wall of the left ventricle and no detectable blood flow in the left coronary artery. Immediate re-initiation of ECC and revascularization of the left coronary artery with a saphenous vein graft were performed. TEE showed a thickened Valsalva sinus wall, indicating a newly developed dissection extending from the proximal anastomosis site, leading to an occlusion of the left coronary ostium. The Valsalva sinus wall near the anastomosis was reinforced with a pair of pledgets to prevent further extension of the dissection (Figure 10b). Perfusion in the left coronary artery recovered, and the patient had an uneventful postoperative course (Figure 10c). In another case, dissection initially extended into the left coronary artery, but the true lumen was predominant (Figure 10d). However, during weaning from ECC, the false lumen gradually enlarged to nearly 50% of the lumen and then occupied more than half before chest closure. Despite these changes, the left ventricle maintained normal contraction. Due to the progressive changes in the coronary artery, coronary artery stenosis was assessed via coronary angiography, which revealed more than 95% stenosis of the left main trunk. Coronary revascularization was performed, and the patient had an uneventful postoperative course. If the left coronary artery had not been monitored with TEE, the patient might have experienced sudden shock or cardiac arrest in the ICU, with findings similar to those in the first case.

Figure 10.

Unexpected Events After Weaning from Extracorporeal Circulation (ECC). a: Occlusion of left main truncus (LMT) before chest closure. b: Possible mechanism of occlusion and subsequent treatment. c: Restored flow in LMT. d: Progressive compression of LMT lumen. AAO: ascending aorta, AV: aortic valve, CAG: coronary angiography.

9. Conclusions

In this chapter, various applications of TEE for managing ATAAD are discussed, including visualization techniques, assessment timing, and target structures. Although TEE requires significant time and effort, the information it provides is crucial for rescuing patients and avoiding complications. This parallels surgical training where practice and experience lead to better outcomes. Despite recent improvements in surgical outcomes, reported mortality rates only reflect patients who undergo surgery. The real prognosis, including those who do not receive surgical treatment, is likely worse, with many survivors suffering from sequelae. Future directions should focus on the following: (1) prevention of ATAAD and (2) precision strategies in surgical treatment. The latest guidelines have, for the first time, addressed the issue of prevention [2]. The personal strategies described in this chapter are a work in progress and will continue to be refined. The author hopes this chapter serves as a catalyst for further advancements in the field.