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Cardiovascular Anesthesiology: Echo Rounds

Thoracic Aortic Stent Migration to False Lumen in Aortic Dissection Detected by Intraoperative Transesophageal Echocardiography

Inoue, Hiroshi MD; Morita, Mariko MD; Ota, Takahisa MD; Ito, Jun MD; Uchida, Hiroaki MD

Author Information
doi: 10.1213/ANE.0000000000001132

Written informed consent was obtained from the patient for publication of this report. A 43-year-old man with type A aortic dissection was transferred to our hospital for emergent surgery. A probe (X7-2t transducer; Philips Healthcare, Andover, MA) was used under general anesthesia for transesophageal echocardiography (TEE). The midesophageal long-axis (LAX) view revealed aortic dissection involving the ascending aorta, causing aortic insufficiency, but no evidence of an intimal tear (Supplemental Digital Content, Supplemental Video 1, The aortic arch LAX and short-axis views revealed a dissection flap involving the innominate, left common carotid, and left subclavian arteries, but no evidence of intimal tear in the aortic arch. The transgastric short-axis view revealed an absence of pericardial effusion. Regional wall motion abnormalities of the left ventricular wall were not noted. The descending aortic LAX view using color-flow Doppler, however, revealed an intimal tear in the descending aorta approximately 5 cm distal to the left subclavian artery (Supplemental Digital Content, Supplemental Video 1,; Fig. 1). Ascending aortic replacement, total arch replacement with a 4-branched graft, and stenting of the descending aorta with an open stent graft (OSG) were planned.

Figure 1
Figure 1:
Preoperative descending aorta long-axis view revealed intimal tear (white arrow), true lumen, and false lumen (A); color-flow Doppler showed blood flow to false lumen through intimal tear (white line). FL = false lumen; TL = true lumen.

After institution of deep hypothermic arrest with antegrade selective cerebral perfusion, the aortic arch was opened. However, direct inspection revealed no evidence of an intimal tear in the ascending aorta or aortic arch, confirming the TEE findings. A 60-mm-long J-open stent® (Japan Lifeline, Tokyo, Japan) was subsequently deployed in the descending aorta under direct inspection of the true lumen. The distal end of the 4-branched graft was sutured to the proximal end of the OSG and distal aortic arch. Cardiopulmonary bypass was then immediately resumed with antegrade perfusion and an aortic cross-clamp. Unexpectedly, intraoperative TEE revealed migration of the distal end of the OSG to the false lumen through the intimal tear, because the selected OSG was too short. Color-flow Doppler showed blood flow to the false lumen (Supplemental Digital Content, Supplemental Video 2,; Fig. 2). The patient’s pharyngeal body temperature remained at 22°C, so deep hypothermic arrest was performed again, and a guidewire was passed to the proximal end of the 4-branched graft through the left femoral artery. Its location in the true lumen was confirmed by TEE. Subsequently, a Conformable Gore® TAG® Thoracic Endoprosthesis (W. L. Gore Associates, Newark, DE) was successfully deployed from the left femoral artery under TEE guidance (Supplemental Digital Content, Supplemental Video 2, This complex procedure is summarized in Figure 3. Postoperative weaning from cardiopulmonary bypass and the perioperative course were uneventful. No paraplegia was observed.

Figure 2
Figure 2:
After deployment, descending aortic long-axis view revealed that end of open stent graft had unexpectedly migrated to false lumen (A, white line); color-flow Doppler revealed blood flow to false lumen through intimal tear (B). FL = false lumen; OSG = open stent graft; TL = true lumen.
Figure 3
Figure 3:
Overall procedure is illustrated. A, First step of repair with 4-branched graft. Distal end of open stent graft unexpectedly migrated to false lumen through intimal tear. B, Second step. Additional stent was deployed through guidewire through left femoral artery. Red arrows indicate arterial cannula of cardiopulmonary bypass, and blue arrows indicate venous cannula. Large asterisk indicates intimal tear. AV = aortic valve; AxA = axillary artery; CCA = common carotid artery; FA = femoral artery; IA = innominate artery; IVC = inferior vena cava; OSG = open stent graft; RA = right atrium; SCA = subclavian artery; SVC = superior vena cava.

Type A aortic dissection usually requires immediate surgical intervention. Contrast-enhanced computed tomography is the most widely used imaging modality in diagnosing aortic dissection, because it is widely available, fast, and noninvasive.1 However, intraoperatively TEE is the most commonly used imaging modality for its diagnosis and for deciding on the type of intervention to be taken. This modality plays a major role in determining the site of the intimal tear, the extent of the dissection, and whether there is flap involvement in the major aortic arch branches; it is also useful in determining whether there is aortic insufficiency, pericardial effusion, or regional wall motion abnormalities.24 The various check points in intraoperative TEE and the imaging plane used for aortic dissection are summarized in Tables 1 and 2. However, intraoperative TEE has certain limitations such as echo dropout because of the stent and limited visualization of the distal ascending aorta due to interference from the trachea and left main bronchus.2,3 Alternative imaging modalities such as epiaortic echography may be more helpful in discerning pathologies of the distal ascending aorta.3 Perioperative TEE for aortic dissection has been reviewed in detail by Tan and Fraser,2 and visualization of the aortic arch has been described in an Echo Didactics.3

Table 1
Table 1:
Preprocedural and Postprocedural TEE Evaluation Points in Aortic Dissection
Table 2
Table 2:
List of Various Intraoperative Transesophageal Echocardiography Views for Evaluation of Aortic Dissection and Their Target Structures

Recently, a hybrid approach using the elephant trunk procedure with an OSG was reported for aortic dissection extending from the distal arch to the descending aorta, as in our patient. However, long-term outcome with this method is unclear.1,5 Fluoroscopy and angiography are usually used with this approach. However, intraoperative TEE is superior to angiography and not just in terms of supplemental imaging. For example, TEE allows detection of spontaneous echo contrast in the false lumen after stent deployment, which suggests closure of the intimal tear, proper positioning of the guidewire in the true lumen, and detection of new intimal tears or endoleak.2,5 Recognition of the true aortic wall, as opposed to the aortic lumen, other aortic pathologies such as atheroma, and clot formation in the false lumen after stent deployment are difficult to detect with fluoroscopy.6 Detection of the true lumen during hybrid procedures is one of the most important roles of intraoperative TEE. Expansion and concavity during systole are the echocardiographic characteristics of the true lumen, whereas a convex shape during systole, expansion during diastole, and possible spontaneous echocardiographic contrast are those of the false lumen.2 Moreover, TEE can distinguish stent endoleak from Dacron porosity. Rocchi et al.5 reported that a cutoff value of 50 cm/s in pulsed wave Doppler allowed differentiation of endoleak from Dacron porosity: with endoleak, blood flows at >50 cm/s, whereas with stent porosity, it flows at <50 cm/s. Detecting occlusion of the left subclavian artery, the most significant predictor of spinal cord ischemia, is another important role for intraoperative TEE.

OSG migration can cause catastrophic complications, such as aortic rupture, end-organ malperfusion, and major aortic arch branch occlusion. The incidence of thoracic stent migration along the aorta is between 1% and 2.8%. Its risk factors include stent oversizing and tortuous seal zone anatomy.6 In a previous Echo Rounds, Wallet et al.7 described how TEE was used to detect another potential complication with the elephant trunk technique, kinking of the prosthesis. However, to the best of our knowledge, there have been no reports of detection of stent migration to the false lumen by intraoperative TEE. Intraoperative TEE plays a very important role in the management of aortic dissection, including in hybrid procedures.

Clinician’s Key Teaching Points

By Martin M. Stechert, MD, Andre-Stephane Lambert, MD, and Martin J. London, MD

  • Acute type A aortic dissection often warrants surgical repair. Depending on the extent of the dissection, repair can be simple involving standard bypass strategies or complex with the use of multiple grafts, cannulation of aortic branch vessels, and deep hypothermic arrest. Open stent grafts are used for a dissection that extends to the descending aorta, with the benefit of avoiding hazardous surgical dissection in the region of the distal aortic arch and a shorter procedure time.
  • The thoracic aorta is anatomically divided into 6 zones, which differ in terms of the ability to be visualized by transesophageal echocardiography (TEE). The proximal ascending aorta (zone 1 and 2), distal aortic arch (zone 5), and descending aorta (zone 6) are usually well imaged, interposition of the distal trachea and left main bronchus usually precludes visualization of the distal ascending aorta (zone 3) and proximal aortic arch (zone 4). This is commonly termed the “blind spot.” Despite this limitation, intraoperative TEE monitoring with 2-dimensional, spectral and color Doppler are useful for defining of true and false aortic lumens, as well as diagnosis of abnormal flow patterns in the aorta or its branches.
  • In this case of a patient with acute type A aortic dissection undergoing complex repair using an extension of a branched aortic arch graft with an open stent graft into the descending aorta, intraoperative TEE monitoring led to early recognition of distal stent migration into the false aortic lumen that was successfully repaired with an endoprosthesis.
  • Because of its unique ability for dynamic assessments of blood flows, TEE is useful for intraoperative monitoring of complex aortic repair.


Name: Hiroshi Inoue, MD.

Contribution: This author helped design the study and prepare the manuscript.

Attestation: Hiroshi Inoue approved the final manuscript.

Name: Mariko Morita, MD.

Contribution: This author helped write the manuscript.

Attestation: Mariko Morita approved the final manuscript.

Name: Takahisa Ota, MD.

Contribution: This author helped write the manuscript.

Attestation: Takahisa Ota approved the final manuscript.

Name: Jun Ito, MD.

Contribution: This author helped write the manuscript.

Attestation: Jun Ito approved the final manuscript.

Name: Hiroaki Uchida, MD.

Contribution: This author helped write the manuscript.

Attestation: Hiroaki Uchida approved the final manuscript.

This manuscript was handled by: Martin J. London, MD.


The authors thank Professor Jeremy Williams of the Department of International Medical Communications at Tokyo Medical University, for his assistance with editing the English in the manuscript.


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