Asian Cardiovasc Thorac Ann 2002;10:167-169
© 2002 Asia Publishing EXchange Pte Ltd
Isolated Idiopathic Pulmonary Artery Aneurysm
Saket Agarwal, MS,
Ujjwal Kumar Chowdhury, MCh,
Anita Saxena, DM1,
Ruma Ray, MD2,
Sanjeev Sharma, MD3,
Balram Airan, MCh
Department of Cardiothoracic and Vascular Surgery
1 Department of Cardiology
2 Department of Pathology
3 Department of Cardiac Radiology Cardiothoracic Sciences Centre All India Institute of Medical Sciences New Delhi, India
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Balram Airan, MCh Tel: 91 11 686 4851 Ext. 4835 Fax: 91 11 686 2663 email: airanbalram{at}hotmail.comDepartment of Cardiothoracic and Vascular Surgery, Cardiothoracic Sciences Centre, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India.
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ABSTRACT
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Aneurysm formation of the main pulmonary artery is rare. Its natural history is not well understood and there are no clear guidelines on optimal treatment. A 20-year-old woman with a huge saccular aneurysm of the main pulmonary artery, underwent repair with a pericardial patch and concomitant reconstruction of the pulmonary valve. The patient was doing well on follow-up at 6 months; echocardiography revealed a good repair with mild to moderate pulmonary regurgitation.
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INTRODUCTION
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Aneurysm of the main pulmonary artery (PA) is a very rare lesion. Its natural history is ill defined and no definite therapeutic approach exists because of its rarity.
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CASE REPORT
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A 20-year-old woman was admitted to hospital because of shortness of breath of 4 months' duration (New York Heart Association functional class II). There was no history of orthopnea, cough, fever, hemoptysis, chest pain, or syncope. On examination, there was mild pallor, a left parasternal heave, and prominent pulsations in the pulmonary area. A grade 4/6 systolic murmur was present in the pulmonary area. Chest radiography revealed a homogenous rounded opacity with clearcut margins in the pulmonary area (Figure 1
). Two-dimensional echo-cardiography showed a large main PA aneurysm. An angiogram (Figure 2) and magnetic resonance imaging (Figure 3) demonstrated a large saccular aneurysm arising from the proximal main PA. The distal main PA, bifurcation, and right and left PAs were normal. There was severe pulmonary regurgitation and moderate PA hypertension with a systolic pressure of 45 mm Hg and a mean pressure of 18 mm Hg on catheterization. A technetium lung scan showed normal physiological distribution of contrast, with a low probability of pulmonary thromboembolism.
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Figure 1. Chest radiograph in posteroanterior view, showing a homogenous rounded opacity with clearcut margins, in the area of the pulmonary artery (PA).
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Figure 2. Cineangiogram showing a large saccular aneurysm (A) arising from the proximal main pulmonary artery.
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Figure 3. Transaxial magnetic resonance image at the level of the first thoracic vertebra, showing a large saccular aneurysm (arrow) arising from the lateral wall of the main pulmonary artery.
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The patient underwent surgery through a median sternotomy. There were diffuse pericardial adhesions. A 6 x 8-cm saccular dilatation of the main PA was seen arising from the lateral wall and involving the anterior half of the annulus. The aneurysm also affected the distal right ventricular outflow tract. The distal main PA was normal with confluent right and left PAs. The aneurysm was opened under cardiopulmonary bypass. There was no intraluminal thrombus or vegetations. Two cusps of the pulmonary valve were normal, the 3rd cusp was partially absorbed into the aneurysm. The redundant sac was excised. The anterior cusp of the pulmonary valve was reconstructed using a pericardial patch, and the right ventricular outflow tract was reconstructed using an onlay patch of pericardium extending across the annulus. The 2 posterior cusps were preserved. Postoperative recovery was uneventful. Chest radiography in the postoperative period showed normal cardiac shadows and lung fields (Figure 4). Prior to hospital discharge, an echocardiogram revealed good aneurysm repair and no gradient across the pulmonary valve. There was mild to moderate pulmonary regurgitation. Histopathology of the resected pulmonary arterial specimen revealed hyalinizing fibrosis and focal calcification. There was focal myxoid degeneration and myointimal proliferation. There was no evidence of arteritis, bacterial or fungal infection in the material examined. At the 6 months follow-up, echocardiography showed mild to moderate pulmonary regurgitation.
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Figure 4. Postoperative chest radiograph in posteroanterior view, showing normal cardiac shadows and lung fields.
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DISCUSSION
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Aneurysms of the main PA are rare entities of both anatomical and surgical fascination. The estimated incidence is 1 in 13,695 necropsies.1 Such aneurysms may be idiopathic, however, associated diseases include congenital defects with intracardiac shunting, right ventricular outflow tract obstruction, tricuspid valve disease in intravenous drug addicts, vascular abnormalities such as arteritis, and PA hypertension.2–5 In this case, there was no evidence of any of these conditions. The histopathological findings in idiopathic PA aneurysms include fragmentation or a decrease of elastic fibers in the media, medial degeneration, and an increase of collagen fibers with a decrease of smooth muscle cells, although normal histology has also been reported.2,4 Some of these histologic findings, such as focal myxoid medial degeneration and myointimal proliferation, were present in this patient.
There are no clear guidelines for management. Con-servative treatment was advocated when there was no left-to-right intracardiac shunt or significant pulmonary arterial hypertension, which resulted in a relatively benign prognosis with an uncomplicated course after 1 to 7 years of follow-up.3 However, progressive enlargement of a pulmonary trunk aneurysm has been reported in the absence of an intracardiac shunt and pulmonary hypertension.6 Thus, the relationship between the rate of aneurysm enlargement and the level of PA pressure is unclear. Surgical options include aneurysmorrhaphy, replacement with a Dacron graft or pulmonary allograft, and combined use of a stentless bioprosthesis and a Dacron prosthesis.2,4,7 Aneurysmorrhaphy is a simple procedure that can be performed quickly. Graft replacement is considered to be more reliable than aneurysmorrhaphy because of potential recurrent dilatation due to the residual aneurysmal wall; one patient required reoperation 9.5 years after aneurysmorrhaphy due to late progressive redilatation of the aneurysm trunk.6 Intrasaccular embolization with steel coils and detachable balloons has also been reported for multiple distal aneurysms.8
This case demonstrated that diagnosis of PA aneurysm is facilitated by magnetic resonance imaging and cineangiocardiography. If a patient has acceptable operative risk, we would recommend surgical repair despite the absence of PA hypertension, to avoid the possibility of progressive aneurysm enlargement and rupture. This is based on the premise that the aneurysm will increase according to Laplace's law and have the potential to rupture.7 Serial noninvasive postoperative follow-up is recommended.
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