the cyst may degenerate and develop a thickened, calci-fied capsule with lymphocytic infiltration, cholesterolclefts, or fibrous tissue. In addition, the fluid may becomethick, bloody, or heterogeneous. Occasionally, the cyst mayenlarge rapidly secondary to hemorrhage or infection.

Thymic cysts are usually asymptomatic and discoveredincidentally on a chest roentgenogram. Radiographically,these lesions appear as smooth, homogeneous, well-circumscribed tumors in the anterior mediastinum with adensity on CT scan approximating that of water [2].Symptomatic thymic cysts resulting in chest pain, cough,hoarseness, dyspnea, and dysphagia have been reported[3–6]. Other unusual presentations have included Hor-ner’s syndrome [7], tracheomalacia [8], and cardiac tam-ponade [9].

The diagnosis and treatment of thymic cysts remainscontroversial. Although thymic cysts are benign lesions,it may be difficult to distinguish them radiographicallyfrom potentially malignant lesions with cystic changes,including thymoma, teratoma, lymphoma, or seminoma.Treatment options include careful observation with closefollow-up, diagnostic or therapeutic aspiration using CTguidance or mediastinoscopy, and surgical explorationand excision. Most authors agree that surgical resectionremains the treatment of choice for definitive diagnosisand cure.

This case of a small, benign thymic cyst causing ob-struction of the left brachiocephalic vein with associatedleft neck swelling was unique, and the intermittentnature of this swelling was unusual. The intermittentswelling may be explained by positional obstruction ofthe left brachiocephalic vein, as the left neck swelling wassignificantly worse while the patient was supine andnearly resolved when the patient was upright. As withmost thymic cysts, surgical resection in this patient

resulted in definitive diagnosis, resolution of symptoms,and cure.

References

1. Davis RD, Oldham HN, Sabiston DC. Primary cysts andneoplasms of the mediastinum: recent changes in clinicalpresentation, methods of diagnosis, management, and re-sults. Ann Thorac Surg 1987;44:229–37.

2. Schnyder P, Gasmsu G. Computed tomography and magneticimaging. In: Givel JC, ed. Surgery of the thymus. Berlin:Springer-Verlag, 1990:217–25.

3. Srikrishna S, Gielchinsky I, Parsonnet V. Mediastinal thymiccysts: a report of three cases. J Thorac Cardiovasc Surg 1995;110:1771–2.

4. Ugur G, Gungor A, Savas I, et al. Huge thymic cysts. J ThoracCardiovasc Surg 1996;112:835–6.

5. Davis JW, Florendo FT. Symptomatic mediastinal thymiccysts. Ann Thorac Surg 1998;46:693–4.

6. McCafferty MH, Bahnson HT. Thymic cyst extending into thepericardium: a case report and review of thymic cysts. AnnThorac Surg 1982;33:503–6.

7. Fraile G, Rodriguez-Garcia JL, Monroy C, Fogue L, Millan JM.Thymic cyst presenting as Horner’s syndrome. Chest 1992;101:1170–1.

8. Case records of the Massachusetts General Hospital: case34—1977. N Engl J Med 1977;297:436–42.

9. Graeber GM, Thompson LD, Cohen DJ, Ronnigen LD, Jaffin J,Zajtchuk R. Cystic lesion of the thymus: an occasionallymalignant cervical and/or anterior mediastinal mass. J ThoracCardiovasc Surg 1984;87:295–300.

Retrocardiac ArteriovenousMalformation Causing RecurrentCerebral IschemiaThomas Busch, MD, Ivan Aleksic, MD, FriederikeSchulze, MD, Horia Sirbu, MD, and Harald Dalichau,MD, PhD

Departments of Thoracic and Cardiovascular Surgery andCardiology, Georg-August-University, Gottingen, Germany

A 28-year-old woman had been suffering from recurrentcerebral embolizations for almost 9 years. A retrocardiacarteriovenous malformation was identified as the source ofemboli. It was supplied by chest wall veins and the rightupper pulmonary vein, connected to the back wall of theleft atrium and a possibly aberrant hepatic vein originatingfrom the abdomen. The aneurysm was resected and allsupplying veins ligated. The vein from below the dia-phragm was implanted into the right atrium. Her postop-erative course was uncomplicated. Long-term follow-upfree from cerebrovascular events.

(Ann Thorac Surg 2000;70:663–5)© 2000 by The Society of Thoracic Surgeons

Accepted for publication Dec 18, 1999.

Address reprint requests to Dr Busch, Department of Thoracic andCardiovascular Surgery, Georg-August-Universitat Gottingen, Robert-Koch-Str 40, 37075 Gottingen, Germany; e-mail: tbusch@gwdg.de.

Fig 2. Computed tomography scan of the chest demonstrating a well-circumscribed, 2.5-cm mass in the prevascular space of the anterior me-diastinum. The tumor is anterior to the left brachiocephalic vein.

663Ann Thorac Surg CASE REPORT BUSCH ET AL2000;70:663–5 CEREBRAL ISCHEMIA DUE TO AV FISTULA

© 2000 by The Society of Thoracic Surgeons 0003-4975/00/$20.00Published by Elsevier Science Inc PII S0003-4975(00)01451-X

Arteriovenous (AV) fistulas represent abnormal connec-tions between arteries and veins, bypassing the cap-

illary bed. Congenital fistulas result from a maldevelop-ment of the common embryonic basis of arteries and veins[1]. The occurrence of congenital AV fistulas has beendescribed in all parts of the body, mainly the head, extrem-ities, and visceral organs [2]. Most thoracic AV fistulas arepulmonary AV fistulas as initially reported by Churton in1897 [3]. However, other thoracic fistulas have been de-scribed [4]. We present a young woman with ischemiclesions of the cerebellum due to recurrent emboli froman arteriovenous aneurysm located in the posteriormediastinum.

A patient was admitted to our hospital with vertigo,profuse sweating, right-sided Horner’s syndrome, paral-ysis of branches of the facial nerve, right-sided paresis ofthe uvula, hoarseness, and dysphagia due to vagal dys-function for the first time at the age of 19. Neurologicalexamination revealed a cerebellar lesion in the area ofthe inferior posterior cerebellar artery. All studies initi-ated to identify the source of embolization were negative.So were all laboratory studies aimed at identifying ahypercoagulable state.

The patient’s previous medical history was remarkablefor a magnetic resonance imaging scan of the chest 5years before, at the age of 14, which had shown anunusual retrocardiac tumor. A relationship with the girl’sneurologic deficits was not considered at that time.

Two years after her initial presentation to our hospital,at the age of 21, the girl experienced transitory ischemicattacks and was diagnosed to have an occluded leftinternal carotid artery without ever having had a stroke.An external/internal carotid artery-bypass was implantedwithout improvement of her neurological symptoms.

Follow-up studies 1 year later, at the age of 22, showeda left-sided stroke in the area of the medial cerebralartery but no further morphologic changes of the brain.Another year later, she was admitted to the hospital dueto embolic occlusion of the left central retinal artery. Atthis point, the retrocardiac tumor was linked to herfrequent embolizations and further diagnostic tests wereordered.

Transthoracic and transesophageal echocardiographyconfirmed a retrocardiac tumor of unknown etiology.Right and left heart catheterization were unremarkable.Computed tomographic scans showed a vascular mal-formation in the posterior mediastinum, possiblyconnected to the left atrium (Fig 1). Venous vesselssupplying this malformation originating from below thediaphragm could not definitely be excluded (Fig 2). Thepatient was suspected to have a systemic-venous mal-formation possibly connected with the right lower pul-monary vein and communicating with the left atrium.Pulmonary angiography showed widened right-sidedpulmonary veins only. Differential diagnosis includedlung sequester and an AV malformation of the venaazygos-hemiazygos-system.

The patient was scheduled for surgery and underwenta right-sided anterolateral thoracotomy. An AV aneu-

rysm was found in the posterior mediastinum. It reachedfrom dorsal of the inferior vena cava behind the hilus ofthe right lung up to the azygos vein. Several veins

Fig 1. Computed tomographic scan of the chest demonstrating a ret-rocardiac arteriovenous (AV) aneurysm communicating with theback wall of the left atrium (arrow).

Fig 2. Computed tomographic scan of the chest demonstrating venoussupply vessels of the malformation above the diaphragm (arrow).

664 CASE REPORT BUSCH ET AL Ann Thorac SurgCEREBRAL ISCHEMIA DUE TO AV FISTULA 2000;70:663–5

supplying blood from the chest wall and multiple smallvessels communicating with the right upper pulmonaryvein and a large connection with the back wall of the leftatrium were identified. Another large venous vessel wasidentified which originated from the abdomen and pen-etrated the diaphragm separately (Fig 3).

All vessels were ligated and divided. The connectingpart to the left atrium was oversewn without extracorpo-real circulation. The AV aneurysm was resected in toto.As we were not able to determine the origin of the largevein coming from below the diaphragm, it was mobilizedand separately implanted into the right atrium.

The postoperative course was uneventful and the pa-tient was discharged on postoperative day 10. She hasbeen followed by our outpatient clinic for the last 5 yearson an annual basis and has not had any more transitoryischemic attacks.

Comment

Congenital AV fistulas frequently become symptomaticduring the second and third decade of life. Cardiac mani-festations are rare. Appropriate therapy is difficult in par-ticular regarding surgical intervention because of the tech-nical difficulties frequently encountered and the high rateof recurrent fistulas. The indication for surgical therapy isgenerally accepted for pulmonary AV fistulas [5], coronaryfistulas and their complications [6], and fistulas originatingfrom the internal mammary artery [7]. Apart from conser-vative approaches, percutaneous intraarterial embolizationof AV fistulas has been attempted with good results [8]. Thispatient was not considered for conservative treatment be-

cause of recurrent emboli which had caused multiple cere-bral infarcts, transitory ischemic attacks, and occlusion ofthe left internal carotid artery. Percutaneous intraarterialembolization was ruled out because of the uncertain pre-operative diagnosis, the high likelihood of a connectionwith the left atrium, and the difficulties to reach thisparticular AV aneurysm.

In case of diagnoses with a grave prognosis, like recur-rent cerebral ischemia, any possible source of embolishould be excluded, in particular in a young patient asdescribed herein. Very rare diseases have to be consideredas well in order to create a reasonable therapeutic conceptfor the patient. We conclude that, if the patient is free fromsymptoms, regular follow-up seems justified. However, incase of cardiac or embolic complications due to AV fistulas,surgical intervention is the therapy of choice.

References

1. Seeger SJ. Congenital arteriovenous anastomoses. Surgery1938;18:264–305.

2. Vollmer JF, Stalker CG. The surgical treatment of congenitalarteriovenous fistulas in the extremities. J Cardiovasc Surg1976;17:340–7.

3. Churton T. Multiple aneurysms of pulmonary artery. BrMed J 1897;1:1223.

4. Soler P, Mehta AV, Garcia OL, Kaiser G, Tamer D. Congenitalsystemic arteriovenous fistula between the descending aorta,azygos vein, and superior vena cava. Chest 1981;5:647–9.

5. Prager RL, Laws KH, Bender HW. Arteriovenous fistula of thelung. Ann Thorac Surg 1983;2:231–9.

6. Bauer HH, Allmendinger PD, Flaherty J, Owlia D, Rossi MA,Chen C. Congenital coronary arteriovenous fistula: spontane-ous rupture and cardiac tamponade. Ann Thorac Surg 1996;5:1521–3.

7. Ancalmo N, Ochsner JL, King TD. Congenital arteriovenousfistula of the internal thoracic artery and chest wall. J PediatrSurg 1976;2:271–2.

8. Keller FS, Rosch J, Baur GM, Taylor LM, Dotter CT, Porter JM.Percutaneous angiographic embolization: a procedure of in-creasing usefulness. Am J Surg 1981;142:5–13.

Azygos Vein DiverticulumVictor M. Caramutti, MD, Javier C. Zaidman, MD,Jose A. Abud, MD, and Eduardo D. Gabe, MD

Department of Cardiovascular Surgery and Department ofClinical Cardiology, Favaloro Foundation, Buenos Aires,Argentina

A 47-year-old woman, diagnosed with a diverticulum ofthe arch of the azygos vein, underwent surgical treat-ment. With nonspecific symptomatology, she presentedone of the most uncommon anomalies of the large veins.

(Ann Thorac Surg 2000;70:665–6)© 2000 by The Society of Thoracic Surgeons

Accepted for publication Dec 27, 1999.

Address reprint requests to Dr Gabe, Department of Clinical Cardiology,Favaloro Foundation, Belgrano 1746 (1093), Buenos Aires, Argentina;e-mail: gabe@cardioweb.net.ar.

Fig 3. Anatomical-topographical drawing of retrocardiac arterio-venous (AV) aneurysm in an anterior–posterior plane. (VCS 5 venacava superior; AVA 5 arteriovenous aneurysm; A 5 pulmonaryartery; V 5 vein; C 5 communication to the back wall of the LA;LA 5 left atrium; RA 5 right atrium; RV 5 right ventricle.)

665Ann Thorac Surg CASE REPORT CARAMUTTI ET AL2000;70:665–6 AZYGOS VEIN DIVERTICULUM

© 2000 by The Society of Thoracic Surgeons 0003-4975/00/$20.00Published by Elsevier Science Inc PII S0003-4975(00)01286-8