Ann Thorac Surg 2009;88:2031-2034. doi:10.1016/j.athoracsur.2009.04.125
© 2009 The Society of Thoracic Surgeons
Case Reports
Aortic Aneurysm Due to Microscopic Polyangiitis
Masaaki Ryomoto, MDa,
Masataka Mitsuno, MDa,
Hiroyuki Nishi, MDa,
Shinya Fukui, MDa,
Yuji Miyamoto, MDa,*,
Hiroyuki Hao, MDb
a Department of Cardiovascular Surgery, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
b Department of Surgical Pathology, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
Accepted for publication April 21, 2009.
* Address correspondence to Dr Miyamoto, 1-1 Mukogawa-cho, Nishinomiya, Hyogo, 663-8501, Japan (Email: y-miyamo{at}hyo-med.ac.jp).
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Abstract
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Aortic aneurysm caused by microscopic polyangiitis is very rare. It typically affects the small vessels. We report the case of a 36-year-old woman who was diagnosed with microscopic polyangiitis as a 26-year-old and who was treated with oral hydrocortisone for 10 years, and had an ascending aortic aneurysm and severe aortic insufficiency without dilatation of the sinus of Valsalva. Laboratory analysis showed high titers of serum perinuclear anti-neutrophil cytoplasmic antibodies. She underwent replacement of the ascending aorta and aortic valve on September 21, 2006. Pathologic analysis of the aneurysmal wall revealed fibrous thickening of the adventitia and intima with severe destruction and atrophy of the media. We believe that this is the first report in the literature of a surgical case of an aortic aneurysm complicated with microscopic polyangiitis.
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Introduction
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Microscopic polyangiitis (MPA) is a systemic vasculitis of the small vessels and involves the expression of perinuclear anti-neutrophil cytoplasmic antibodies (p-ANCA). Microscopic polyangiitis was defined in the Chapel Hill Consensus Conference in 1994 as a necrotizing vasculitis that affects small vessels (namely, capillaries, venules, or arterioles) and involves the kidney and lung [1]. It is commonly believed that the aorta is rarely affected by MPA. We believe that this report is the first surgical case of a patient undergoing graft replacement of the ascending aorta and aortic valve replacement to treat an aneurysm in the ascending aorta and aortic insufficiency that resulted from MPA.
A 36-year-old woman, who visited our hospital in December 2005, complained of dyspnea on exertion. In 1995, she was diagnosed with MPA, because she had proteinuria, hematuria, hemoptysis, and skin induration, which was assessed by skin biopsy, demonstrating acute necrotizing vasculitis of the subcutaneous small arteries (Figs 1A and 1B). She has been taking oral hydrocortisone since then. At that time she was also found to have mild aortic regurgitation without dilatation of the ascending aorta, which was identified by echocardiography. On admission in September 2006, she had a diastolic murmur at the third intercostal space of the left sternal border. Peripheral arterial pulsation was normal. Laboratory studies showed slight anemia (hemoglobin, 10.5 g/dL), a raised C-reactive protein of 2.2 mg/dL, and serum p-ANCA levels of 200 EU (normal level, 0 to 19 EU). Urine analysis showed normal findings. Transthoracic echocardiography revealed severe aortic regurgitation with left ventricular dysfunction (ejection fraction, 36%; left ventricular end-systolic volume, 123 mL). A chest computed tomographic scan showed a 50-mm aneurysm of the ascending aorta without dilatation of the sinotubular junction. An aberrant left subclavian artery was also detected. The aortic arch and descending aorta were normal (Fig 2). She was then switched to a much stronger hydrocortisone treatment for MPA, and her MPA was well controlled (p-ANCA, decreased to 52 EU; C-reactive protein, 0.2 mg/dL). Then she underwent an operation on September 21, 2006.
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Fig 1. (A) A skin biopsy specimen demonstrating acute necrotizing vasculitis of the small arteries in subcutaneous tissue. (B) Higher magnification of a small artery shows massive infiltration of leukocytes and marked destruction of the arterial wall. (C–E) Aneurysmal wall of the ascending aorta shows fibrous thickening of the adventitia and intima. Atrophy of the aortic media with destruction of elastic fibers is prominent. (F) Endarteritis obliteration of vasa vasorum in the adventitia. (A, B, and D: Hematoxylin & eosin; and C, E, and F: Elastica van Gieson; photomicrograph A and C shown at x10, B and F at x50, and D and E at x100, respectively.)
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Fig 2. Preoperative computed tomographic scans are shown. (A) The aortic arch and descending aorta were of normal sizes. An aberrant left subclavian artery (asterisk) can be seen arising from the descending aorta. (B) The ascending aorta was severely enlarged to 5 cm in diameter. (C) The ascending aorta was enlarged from just above the sinotubular junction (STJ) (white line).
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Conventional cardiopulmonary bypass techniques with moderate hypothermia were used. Although the ascending aorta was markedly dilated, the sinotubular junction and the sinus of Valsalva were not enlarged, and the aortic valve appeared floppy. Therefore, aortic valve replacement with a 21-mm Sorin Bicarbon Slimline (Sorin Biomedica Cardio S.r.I., Saluggia, Italy) and graft replacement of the ascending aorta with a 20-mm Hemashield vascular graft (Boston Scientific Medi-tech, Wayne, NJ) were performed. Histologic analysis showed marked fibrous thickening of the adventitia and intima of the aneurysmal wall. Thinning of media was prominent with destruction and absence of elastic lamellae, which were focally replaced by fibrous tissue (Fig 1C). No remarkable infiltration of inflammatory cells was identified in the media of the aneurysmal wall (Figs 1D, 1E). End-artery obliteration of the vasa vasorum was identified without giant cell infiltration (Fig 1F). These findings suggest burned-out lesion of aortitis, but indicate that neither atherosclerosis nor degenerative disease was responsible for her condition. In the aortic valves, the elastic fibers decreased to the same extent as the aneurysmal wall. Her postoperative course was uneventful and she was discharged from our hospital on postoperative day 23; she has been doing well for 2.5 years since the operation.
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Comment
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Microscopic polyangiitis is a systemic vasculitis that affects small vessels (capillaries, venules, arterioles, and arteries), particularly those of the kidney or lung, according to the proposal of the Chapel Hill Consensus Conference in 1994 [1]. Based on this proposal, Wegener's granulomatosis and Churg-Strauss syndrome also involve small vessels and are associated with ANCA. However, MPA must be identified based on the absence of granulomatous inflammation, which is observed in patients with Wegener's granulomatosis and Churg-Strauss syndrome. Our case was diagnosed with MPA in 1995 based on the following symptoms and laboratory data: proteinuria, hemoptysis, and high titers of serum p-ANCA. Furthermore, no granulomatous inflammation was observed in the skin induration by histologic analysis.
Microscopic polyangiitis rarely involves large vessels such as the aorta. Chirinos and colleagues [2] reported a case of aortic dissection of the descending aorta due to MPA. That case died as a result of a right hemithorax that had resulted from the rupture of the dissecting aneurysm. However, there are no reports of operations for MPA-associated aortic aneurysm. In an animal model, Angouras and colleagues [3] reported that impaired vasa vasorum flow of the aorta leads to abnormal morphology of the elastin and the collagen fibers of the media, resulting in increased aortic stiffness, which causes aortic dissection. The histologic findings of the aneurysmal wall in our case manifested severe stenosis of the vasa vasorum owing to the intimal hyperplasia and the decreased numbers of elastic fibers in the media, which are representative findings in MPA. Fortunately, our case did not develop an aortic dissection; however, the extremely vulnerable media could have been the cause of the development of the ascending aortic aneurysm.
We performed an aortic valve replacement and graft replacement of the ascending aorta because there was no dilatation of the sinus of Valsalva. It was feasible to use a mechanical valve in this case because the patient did not plan pregnancy. She has been taking oral corticosteroid therapy continuously to treat her MPA and the whole aorta is checked bi-annually by computed tomographic scanning.
Here we have described the first surgical case undergoing graft replacement of the ascending aorta and aortic valve replacement to treat an aneurysm of the ascending aorta and aortic insufficiency that resulted from MPA.
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References
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- Jennette JC, Falk RJ, Andrassy K, et al. Nomenclature of systemic vasculitides. Proposal of an international consensus conference. Arthritis Rheum 1994;37:187-192.[Medline]
- Chirinos JA, Tamariz LJ, Lopes G, et al. Large vessel involvement in ANCA-associated vasculitides: report of a case and review of the literature Clin Rheumatol 2004;23:152-159.[Medline]
- Angouras D, Sokolis DP, Dosios T, et al. Effect of impaired vasa vasorum flow on the structure and mechanics of the thoracic aorta: implications for the pathogenesis of aortic dissection Eur J Cardiothorac Surg 2000;17:468-473.[Abstract/Free Full Text]
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Abstract
Introduction
