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J Thorac Cardiovasc Surg 2007;133:834-835
© 2007 The American Association for Thoracic Surgery
Brief Communication |
Department of Cardiovascular Surgery, Kanto Medical Center NTT EC, Tokyo, Japan.
Received for publication October 17, 2006; accepted for publication November 9, 2006. * Address for reprints: Yoshitsugu Nakamura, MD, Department of Cardiovascular Surgery, Kanto Medical Center NTT EC, 5-9-22 Higashigotanda, Shinagawa-ku, Tokyo 141-8625, Japan. (Email: nakamura{at}kmc.mhc.east.ntt.co.jp).
We report a surgical case of a large thrombosed azygos vein aneurysm causing severe pulmonary embolism. The aneurysm diminished spontaneously by closing its connection with the superior vena cava.
A 37-year-old woman was admitted with chest pain and palpitations. A superior vena caval aneurysm had been diagnosed 2 years ago during the patient’s left thyroid lobe resection. Her medical history was unremarkable except for thyroid disease. Furthermore, no significant trauma was recorded. Her cardiac, renal, and hepatic functions were normal. A chest radiograph showed mediastinal enlargement occupying the right upper lung field (Figure 1, A). Computed tomography (CT) revealed a huge thrombosed saccular aneurysm of 11 x 9 cm at the azygos vein arch (Figure 2, A). The thrombus protruded into the superior vena cava (SVC), and bilateral massive pulmonary embolism was detected (Figure 2, B). Medical therapy for anticoagulation was not effective. Therefore, an emergency operation was performed. Through a median sternotomy, a cardiopulmonary bypass was established by right femoral and left brachiocephalic vein drainage cannulations and an ascending aortic return cannulation. The SVC was snared and intercepted at the junction to the right atrium and left brachiocephalic vein. The SVC was longitudinally incised. The orifice of the azygos vein was 2 x 2 cm on the posterior wall of the SVC. The protruding thrombus was removed from the SVC. The orifice was closed with a 4-0 polypropylene running suture. The aneurysm itself was not removed. The right pulmonary artery was incised, and the embolectomy was completed. The postoperative course was uncomplicated. Four years after the operation, the shadow of the aneurysm disappeared on chest radiograph (Figure 1, B), and the aneurysm diminished to 15 mm in diameter on CT.
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Aneurysm of the azygos vein is rare.1
Most reported cases have no specific symptoms.1,2 To the best of our knowledge, pulmonary embolism occurring in this exceptional aneurysm has never been reported.
There are 3 main causes of azygos vein aneurysm. First, there is azygos vein dilatation caused by pressure and volume load, such as portal hypertension or inferior vena caval occlusion; this type of aneurysm is usually fusiform.3 Second, there is traumatic pseudoaneurysm, including blunt injury or catheter insertion into the azygos vein. Third, there is idiopathic saccular aneurysm; this is assumed to be a congenital aneurysm that is caused by the development of a remnant of an embryologic vein connecting the transverse part of the azygos vein. We believe our case was idiopathic, that is, congenital from the viewpoint of its form and medical history.
The treatment strategy is not clear in azygos venous aneurysm. Most cases of saccular aneurysm have been reported to be removed through a conventional right thoracotomy or thoracoscopic approach.4 In our case with pulmonary embolism, a median sternotomy was mandatory for pulmonary embolectomy. The aneurysm was large and had some branches that were difficult to occlude through a median sternotomy. Therefore, we simply excluded the aneurysm from the SVC by closing its orifice to prevent the recurrence of pulmonary embolism. We believe that surgical removal of venous aneurysms is not always necessary because the venous aneurysm is in a low-pressure system. In fact, follow-up with CT for 4 years revealed a significant spontaneous reduction in size of the aneurysm.
One important point is the differential diagnosis of a neoplastic tumor of the azygos vein, for example, leiomyosarcoma.5 Definite evaluation by contrast-enhanced CT helps to distinguish between these 2 masses. If vascular neoplasma is suspected by preoperative CT, the mass should be completely removed.
An azygos vein aneurysm is extremely uncommon; however, if it is thrombosed, surgical therapy is necessary to prevent pulmonary embolism. The exclusion technique of the aneurysm can be 1 surgical option.
References
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