Ann Thorac Surg 2001;72:1377-1378
© 2001 The Society of Thoracic Surgeons
Case report
Aneurysmal change in an internal mammary artery–pulmonary artery fistula
Yoshikazu Hachiro, MDa,
Satoru Sugimoto, MDa,
Nobuyuki Takagi, MDa,
Tomio Abe, MD, PhDa
a Department of Thoracic and Cardiovascular Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
Accepted for publication September 25, 2000.
Address reprint requests to Dr Hachiro, Department of Thoracic and Cardiovascular Surgery, Sapporo Medical University School of Medicine, South 1, West 16, Chuo-ku, Sapporo 060-8543, Japan
e-mail: hachiro{at}sapmed.ac.jp
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Abstract
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We treated a rare case of aneurysm of the internal mammary artery–pulmonary artery fistula in a 32-year-old woman with unrepaired pulmonary atresia and ventricular septal defect. This aneurysm communicated with the pulmonary artery system through an aortopulmonary collateral. Aneurysmectomy was successful.
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Introduction
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Aneurysms of the collateral arteries to pulmonary arterial circulation are rare. We treated a patient with pulmonary atresia and ventricular septal defect who had an aneurysm of a branch of the left internal mammary artery that communicated with the pulmonary artery system.
A 32-year-old woman with pulmonary atresia and ventricular septal defect and aortopulmonary collateral arteries presented with a retrosternal mass. The patient had been followed up at our hospital since her congenital malformation was diagnosed by cardiac catheterization at age 6 years. Because she had minimal symptoms and lacked a true pulmonary arterial system, no palliative procedures had been done.
Angiography was done after a routine computed tomographic scan established that the retrosternal mass was of vascular origin (Fig 1). The patient was admitted to the hospital for further evaluation and treatment. At admission, the patient had clubbing of the fingers. Systemic oxygen saturation was 65%, with a partial arterial oxygen tension of 37.4 mm Hg. Pulmonary blood flow was supplied by the collateral vessels, such as the internal mammary artery, the subclavian artery, the bronchial artery, the coronary artery, and the descending aorta. The major source of supply to the pulmonary arterial circulation could not be identified by angiography. Digital subtraction angiography showed that the mass was a 25 x 15-mm saccular aneurysm of a branch of the left internal mammary artery that communicated with a pulmonary artery (Fig 2).
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Fig 1. Contrast-enhanced axial computed tomographic scan confirming the vascular nature of the anterior mediastinal mass (arrow).
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Fig 2. Selective left internal mammary arteriogram showing the presence of a saccular aneurysm (arrow).
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The aneurysmectomy was approached through a median sternotomy. The aneurysm was identified at the deep surface of the left side of the sternum at the level of the innominate vein. The inflow vessel appeared to be a branch of the left internal mammary artery. Temporary clamping of the inflow and outflow vessels did not affect the patient’s hemodynamics or arterial saturation, so an en bloc aneurysmectomy was done successfully. The patient’s recovery was uneventful.
Pathologic examination of the surgical specimen found a typical saccular aneurysm. The intima was enlarged, and the vessel wall was fibrotic; there was no evidence of vascular inflammation. Additional findings included loss of elastic tissue within the wall of the aneurysm (Elastic-Van Gieson stain).
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Comment
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Recent advances in cardiac surgery have made it possible for most patients with pulmonary atresia and ventricular septal defect to have palliative procedures or total repair. However, some cases of extreme pulmonary artery hypoplasia might not be amenable to surgical correction because pulmonary blood flow depends on aortopulmonary collaterals in patients with unrepaired pulmonary artery atresia and ventricular septal defect.
Fistulas between one of the internal mammary arteries and a pulmonary artery are rare [1]. Collateral arteries that provide pulmonary blood flow gradually stenose secondary to intimal hyperplasia, polycythemia, hyperviscosity, and lack of growth [2]. In this case, unexpectedly, the left internal mammary artery supplying a collateral vessel increased in diameter, but neither systemic hypertension nor arteriosclerosis developed.
Reported pathology of the internal mammary artery includes fibromuscular hyperplasia, atherosclerotic disease, posttraumatic false aneurysms, and posttraumatic arteriovenous fistulas [3–6]. Our patient had no history of chest trauma, infection, or systemic hypertension, so the etiology of this aneurysm remains undetermined but probably is related to the patient’s congenital anomalies.
The choice of surgery over other types of intervention warrants discussion. Embolization by interventional radiology, such as coil occlusion, is a safe, relatively simple technique that can obviate the need for an operation in many patients. In this case, we believed that surgery was indicated because selective occlusion of a branch of the left internal mammary artery was deemed impractical, and more importantly, inadvertent occlusion of other pulmonary artery collaterals could be life threatening.
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References
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Hearne S.F., Burbank M.K. Internal mammary artery-to-pulmonary artery fistulas. Case report and review of the literature. Circulation 1980;62:1131-1135.[Abstract/Free Full Text]
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Thiene G.T., Frescura C., Bini R.M., Valente M., Gallucci V. Histology of pulmonary arterial supply in pulmonary atresia with ventricular septal defect. Circulation 1979;60:1066-1074.[Abstract/Free Full Text]
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Den Otter G., Stam J. Aneurysm of internal mammary artery. Thorax 1978;33:526-527.[Abstract/Free Full Text]
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Wildhirt S., Eckel L., Beyersdorf F., Satter P. Atherosclerotic aneurysm of the right internal mammary artery presenting as a mediastinal mass. J Thoracic Cardiovasc Surg 1994;107:1535-1536.[Free Full Text]
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Kruyt P.M., Winter L.H., Koning J. A pseudo-aneurysm of the internal mammary artery: a very rare complication of subclavian vein puncture. Eur J Vasc Surg 1993;7:349-351.[Medline]
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Millner R.W., Guvendik L., Blauth C., Treasure T., Pepper J.R. False aneurysm of the right internal mammary artery. Ann Thorac Surg 1991;51:831-832.[Abstract/Free Full Text]
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Abstract
Introduction
