Ann Thorac Surg 2008;85:2127-2128. doi:10.1016/j.athoracsur.2007.12.054
© 2008 The Society of Thoracic Surgeons
Case Reports
Ascending Aortic Dissecting Aneurysm with Isolated Right Pulmonary Arterial Medial Intramural Hematoma
Jiunn-Jye Sheu, MDa,
Morgan Fu, MDb,
Fan-Yen Lee, MDa,
Shu-Hang Ng, MDc,
Yung-Liang Wan, MDc,
Sheung-Fat Ko, MD*,c
a Department of Cardiovascular and Thoracic Surgery, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University, College of Medicine, Kaohsiung, Taiwan
b Department of Cardiology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University, College of Medicine, Kaohsiung, Taiwan
c Department of Radiology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University, College of Medicine, Kaohsiung, Taiwan
Accepted for publication December 18, 2007.
* Address correspondence to Dr Ko, Department of Radiology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, 123 Ta-Pei Rd, Niao-Sung Hsiang, Kaohsiung Hsien, 833, Taiwan (Email: sfa.ko{at}msa.hinet.net).
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Abstract
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On rare occasions, acute aortic dissection may cause pulmonary artery obstruction when there is aortic rupture with hemorrhage into the common adventitia of the aorta and pulmonary artery. We report an extremely unusual case of an ascending aortic dissecting aneurysm associated with an isolated medial intramural hematoma in the right pulmonary artery in an 86-year-old woman with clinical manifestations mimicking pulmonary embolism. We believe that this rare pulmonary arterial complication of aortic dissection without involvement of the common adventitia has not been previously described.
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Introduction
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Acute type A aortic dissection is a life-threatening condition that requires early diagnosis and prompt surgical treatment. Common complications include cardiac tamponade or hypovolemia due to aneurysm rupture, and cerebral, renal, mesenteric or extremity ischemia, secondary to further dissection and occlusion of the aortic branches. Although uncommon, there are reports of involvement of the pulmonary artery due to aortic dissection with penetration and extension of a hematoma beneath the common adventitia of the aorta and pulmonary artery or external compression by a dilated ascending dissecting aneurysm [1–4]. We report an exceptionally unusual case of ascending aortic dissecting aneurysm with an isolated medial intramural hematoma (IMH) of the right pulmonary artery (RPA).
An 86-year-old woman with a 20-year history of hypertension was admitted to our hospital due to chest discomfort for 1 week and aggravated dyspnea for 3 days. Transthoracic echocardiography revealed a pulmonary arterial pressure of 70 mm Hg, indicative of severe pulmonary hypertension. Laboratory examinations showed no abnormalities except for mild leukocytosis and an elevated D-dimer level (447 ug/L; normal 250 ug/L). A chest roentgenogram showed cardiomegaly, a widened aorta, left lower lung consolidation, and pleural effusion. Under the impression of pulmonary embolism, she underwent thoracic multidetector computed tomography (MDCT), which revealed an intimal flap and a partially thrombosed false lumen in the ascending aorta, indicative of a type A dissection (Fig 1). At the level of the RPA, precontrast MDCT demonstrated a partially thrombosed aortic false lumen and a slightly hyperattenuated crescent lesion along the posterior RPA wall (Fig 2A). Postcontrast MDCT demonstrated extrinsic compression on the RPA by a focal bulge in the posterior aspect of the ascending dissecting aortic aneurysm and a suspicious thrombus along the RPA, contributing to marked RPA luminal narrowing (Fig 2B). Surgical findings confirmed MDCT findings of an ascending aortic dissection with aneurysm formation and a partially thrombosed false lumen, but there was no periaortic or mediastinal hematoma. The patient also had pericardial effusion with clear fluid, inflammatory changes in the left lower lung lobe and left pleural effusion. The ascending dissecting aneurysm compressed the adjacent RPA, which looked mildly swollen. However, there was no hematoma beneath the common adventitial layer of the aorta and pulmonary artery. The RPA was opened anteriorly at the proximal part and no intraluminal thrombus was found. Instead, we found an IMH in the medial layer of the inferior and posterior walls of the RPA at the level where the aorta crosses over the RPA. The pulmonary artery intima covering this hematoma was intact. A secondary incision was gently performed from externally through the adventitia of the inferior edematous part of the proximal RPA to expose the medial IMH, which was subsequently evacuated. An autologous pericardial patch repair with coverage of the anterior and inferior incisions was then performed. Subsequently, graft replacement of the ascending aorta (28 mm woven double velour vascular graft, Hemashield [Boston Scientific, CA]) and aortic valve re-suspension were performed. After surgery, the pulmonary arterial pressure dropped to 30 mm Hg. The patient eventually recovered after 5 weeks.
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Fig 1. Postcontrast multidetector computed tomographic scan shows an intimal flap (black arrow) and a partially thrombosed false lumen (open arrows) in the ascending aorta. Also note the pericardial effusion, left lower lung consolidation, and left side pleural effusion.
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Fig 2. (A) Precontrast multidetector computed tomographic scan shows a hyperdense thrombus (open arrows) in the anterolateral part of the ascending aorta and a slightly hyperdense lesion (white arrows), initially interpreted as a pulmonary thrombus, along the posterior wall of the right pulmonary artery. (B) Postcontrast multidetector computed tomography shows an ascending aortic aneurysm (black arrow) pressing on the right pulmonary artery and a surgically proven intramural hematoma (white arrows) with narrowing of the right pulmonary arterial lumen. Note the partially thrombosed aortic false lumen (open arrows).
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Comment
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Acute dissecting aneurysm of the ascending aorta complicated by stenosis of the RPA was first described by Buja and colleagues [1]. A few more cases of this rare complication of aortic dissection have been subsequently reported. Most patients were initially believed to have suffered from pulmonary embolism, as in the present case [2–4]. Anatomically, the pulmonary artery has relatively lower pressure and is susceptible to compression by a hematoma when an aortic dissection extends beneath the common tunica adventitia shared by the aorta and pulmonary artery [2–4]. On the other hand, owing to the close proximity of the RPA and ascending aorta, the RPA can be compressed by a dilated ascending aortic dissecting aneurysm itself, with subsequent decreased pulmonary arterial flow and pulmonary thrombus formation [3].
Multidetector computed tomography has become the imaging modality of choice for aortic dissection and its variants, IMH, penetrating atherosclerotic ulcers, and acute pulmonary embolism [5]. Multidetector computed tomography may allow demonstration of aortic dissection or IMH with penetration beneath the common adventitia and extension of the hematoma along the pulmonary artery [2, 4]. If this rare scenario is not recognized, this subadventitial hematoma may be misinterpreted as a mediastinal hematoma [3]. In our case, MDCT offered an accurate diagnosis of a clinically unexpected ascending aortic dissecting aneurysm with compression of the RPA. Although MDCT could not definitively discriminate an isolated RPA IMH from a pulmonary thrombus, it did exclude a mediastinal hemorrhage. Instead of thrombolytic therapy, which could have been catastrophic, surgery was mandated as soon as MDCT demonstrated an ascending aortic dissection. Fortunately, graft replacement of the ascending aorta, removal of the RPA IMH and autologous pericardial patch repair of the pulmonary artery were successful in our patient. We believe that this is the first report of an ascending aortic dissecting aneurysm with isolated RPA medial IMH. We postulate that the ascending dissecting aortic aneurysm of the patient, although rare, might have compressed and exerted force on the contiguous RPA during pulsation, leading to medial IMH and acute pulmonary hypertension.
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References
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- Buja LM, Ali N, Fletcher RD, Roberts WC. Stenosis of the right pulmonary artery: a complication of acute dissecting aneurysm of the ascending aorta Am Heart J 1972;83:89-92.[Medline]
- De Silva RJ, Hosseinpour R, Screaton N, Stoica S, Andrew T, Goodwin AT. Right pulmonary artery occlusion by an acute dissecting aneurysm of the ascending aorta J Cardiothorac Surg 2006;1:29.[Medline]
- Neri E, Toscano T, Civeli L, Capannini G, Tucci E, Sassi C. Acute dissecting aneurysm of the ascending thoracic aorta causing obstruction and thrombosis of the right pulmonary artery Tex Heart Inst J 2001;28:149-151.[Medline]
- Sueyoshi E, Sakamoto I, Uetani M, Matsuoka Y, Suenaga E. CT findings of ruptured intramural hematoma of the aorta extending along the pulmonary artery Cardiovasc Intervent Radiol 2007;30:321-323.[Medline]
- Chiles C, Carr JJ. Vascular diseases of the thorax: evaluation with multidetector CT Radiol Clin North Am 2005;43:543-569.[Medline]
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Abstract
Introduction
