J Thorac Cardiovasc Surg 2006;132:1228-1230
© 2006 The American Association for Thoracic Surgery
Dissection of Kommerell's aneurysm mimicking aortic arch dissection on echocardiography: Multislice computed tomographic diagnosis
Tze-Yu Lee, MDa,
Shu-Hang Ng, MDa,
Chi-Di Liang, MDb,
Ming-Jang Hsieh, MDc,
Sheung-Fat Ko, MDa,*
a Department of Radiology, Chang Gung Memorial Hospital- Kaohsiung Medical Center, Chang Gung University, College of Medicine, Kaohsiung, Taiwan
b Department of Pediatric Cardiology, Chang Gung Memorial Hospital- Kaohsiung Medical Center, Chang Gung University, College of Medicine, Kaohsiung, Taiwan
c Department of Cardiovascular and Thoracic Surgery, Chang Gung Memorial Hospital- Kaohsiung Medical Center, Chang Gung University, College of Medicine, Kaohsiung, Taiwan.
Received for publication June 23, 2006; revisions received July 14, 2006; accepted for publication August 8, 2006.
* Address for reprints: Sheung-Fat Ko, MD, Department of Radiology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, 123, Ta-Pei Road, Niao-Sung Hsiang, Kaohsiung Hsien, 833, Taiwan. (Email: sfa.ko{at}msa.hinet.net; sfatko{at}adm.cgmh.org.tw).
Right-sided aortic arch (RAA) is an uncommon anomaly that occurs in about 0.04% to 0.1% of the population.1
RAA is generally asymptomatic but can occasionally cause acute aortic symptoms because of dissection or aneurysmal rupture.1 Recent studies using imaging modalities, including transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), multislice computed tomography (MSCT), or magnetic resonance imaging, have shown high accuracy in the diagnosis of acute aortic lesions.2-4 However, the diagnostic pitfalls of acute aortic diseases on echocardiography in patients with aortic arch anomalies have rarely been described.5 We report the MSCT diagnosis of a case of RAA associated with dissection of Kommerell's aneurysm (KA) mimicking aortic arch dissection on echocardiography.
Clinical Summary
A 48-year-old man was admitted to the emergency department because of acute sharp chest pain that radiated to his back. He had a 10-year history of hypertension and hyperuricemia. Physical examination was unremarkable, except for increased blood pressure of 168/98 mm Hg. Electrocardiography revealed slight ST-T elevation in the V1 to V3 leads. Chest radiography showed a widened mediastinum with an RAA and right descending thoracic aorta. Emergency TTE showed an intimal flap in the widened aortic arch (Figure 1) and the descending thoracic aorta indicative of aortic dissection. Possible retrograde dissection to the ascending aorta was also suspected. Subsequent TEE revealed similar findings, but the ascending aorta still could not be definitively evaluated. Emergency surgical intervention was planned under the impression of type A aortic dissection. Before the operation, MSCT (4-detector-row, Volume Zoom; Siemens, Forchheim, Germany) demonstrated an RAA with a right descending aorta, a Kommerell's diverticulum with aneurysmal dilatation, and an aberrant left subclavian artery (ALSA; Figure 2). Dissection of the KA with intimal flaps was clearly demonstrated on axial and multiplanar reconstructed images, corresponding to the misdiagnosed aortic arch dissection on TTE and TEE. The entrance tear was identified at the KA. Extension of the intimal flaps to the ALSA, the right descending aorta, and the abdominal aorta was noted, with sparing of the RAA and ascending aorta, indicating type B aortic dissection. The patient refused surgical treatment of the KA and was conservatively managed with blood pressure and pain control. He was discharged 4 days later and remained in stable condition during regular follow-up for 3 years.
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Figure 1. Transthoracic echocardiography shows an intimal flap in an aortic arch–like structure (open arrows), which is actually a Kommerell's diverticulum (arrows).
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Figure 2. A, Axial contrast-enhanced computed tomography shows a Kommerell's aneurysm (open arrow) with an intimal flap (arrows) extending to the aberrant left subclavian artery (ALSA). Note that the right ascending aorta (AsAo) is not affected. B, Oblique coronal reconstruction view shows the dissection (arrows) of the Kommerell's aneurysm (open arrows) involving the ALSA, right descending thoracic aorta (RAo), and abdominal aorta. Note that the aortic arch is spared.
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Discussion
Approximately 40% of RAA cases are associated with an aberrant subclavian artery (ASA) originating from a diverticulum, so-called Kommerell's diverticulum, which is formed by a remnant of the left dorsal aorta.1 Most patients with RAA are asymptomatic. However, RAA and aortic diverticulum can be confused with acquired aortic diseases, leading to unnecessary surgical intervention.1,5 Although rare, atherosclerotic changes of ASA and KA can lead to dissection or aneurysmal dilatation. In a review of 32 cases of RAA associated with KA and ASA reported from 1966 through 2002, 12 were associated with aortic dissection, and 2 included aneurysmal rupture.1 Therefore a precise anatomic delineation of RAA is important for appropriate therapy.
TEE, MSCT, and magnetic resonance imaging are highly accurate in evaluating aortic dissection, and catheter angiography is now used primarily for treating complications.2,3 TEE has been reported to be the diagnostic imaging modality of choice in the unstable patient because it can detect ascending aortic dissection, which necessitates urgent surgical intervention.3 Intraoperative TEE has also been recommended as a primary diagnostic modality to rule out aortic dissection.4 However, it should be cautiously applied in assessing RAA because of the greater potential for unfamiliarity of the examiner with such complicated anatomy.5 Furthermore, TEE examination of RAA is easily interfered with by the trachea, which lies between the esophagus and the ascending aorta. In the present case TEE not only failed to identify the RAA and the ascending aorta but also misinterpreted the KA dissection as an aortic arch dissection. On the contrary, MSCT with multiplanar reconstruction offered a comprehensive anatomic delineation of the RAA, KA, and ALSA. Most importantly, it demonstrated the entrance tear of the dissection at the KA, showed the exact extent of the dissection flaps, and excluded the involvement of the aortic arch and ascending aorta. These findings established the definitive diagnosis of type B dissection. Instead of immediate surgical intervention, the patient was successfully managed with conservative treatment. Although the patient refused elective surgical resection of the KA, he remained in good condition during 3 years of follow-up.
In summary, echocardiographic findings of RAA and KA can lead to confusion. MSCT with multiplanar reconstruction can allow comprehensive elucidation of the congenital arch anomaly associated with acute aortic diseases, facilitating appropriate treatment.
References
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- Kapustin AJ, Litt HI. Diagnostic imaging for aortic dissection. Semin Thorac Cardiovasc Surg 2005;17:214-223.[Medline]
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- Eltzschig HK, Rosenberger P, Lekowski Jr RW, Scott JD, Locke A, Shekar PS, et al. Role of transesophageal echocardiography in patients with suspected aortic dissection. J Am Soc Echocardiogr 2005;18:1221.[Medline]
- Ko SF, Ng SH, Fu M, Lo PH, Cheng YF, Lee TY. Dissection of retroesophageal aortic diverticulum and descending aorta in a patient with right aortic arch: magnetic resonance demonstration. Cardiovasc Intervent Radiol 1996;19:438-441.[Medline]
