Asian Cardiovasc Thorac Ann 2002;10:359-361
© 2002 Asia Publishing EXchange Pte Ltd
Severe Unilateral Pulmonary Vascular Changes in Child With Polysplenia
Katsuhide Maeda, MD,
Shigeo Yamaki, MD1,,
Arata Murakami, MD,
Jun Nakajima, MD,
Toshio Hishi, MD,
Shinichi Takamoto, MD
Department of Cardiothoracic Surgery
2 Department of Pediatrics Faculty of Medicine University of Tokyo Tokyo, Japan
1 Department of Cardiology Katta General Hospital Shiroishi, Fukushima, Japan
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For reprint information contact: Katsuhide Maeda, MD Tel: 81 3 5800 8654 Fax: 81 3 5684 3989 email: maedak-tky{at}umin.ac.jp Department of Cardiothoracic Surgery, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
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ABSTRACT
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A 12-year-old boy with polysplenia and single ventricle experienced recurrent episodes of pneumonia, hemoptysis, and pulmonary hypertension. Unilateral pulmonary vein obstruction was diagnosed, and a left pneumonectomy was performed. Microscopy of the resected specimen revealed pulmonary veno-occlusive disease in the small pulmonary venules, and old arteritis in the small pulmonary arteries.
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INTRODUCTION
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Pulmonary veno-occlusive disease (PVOD) is a rare cause of pulmonary hypertension, which usually affects the lungs bilaterally in children and young adults.1 The clinical course and histological characteristics of a case of unilateral PVOD with polysplenia are described.
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CASE REPORT
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Soon after birth, a cyanotic baby boy was diagnosed with polysplenia, single ventricle, transposition of the great arteries, patent ductus arteriosus, and pulmonary atresia, by echocardiography. Catheterization at 7 months showed Qp/Qs of 0.43 and ductus-dependent pulmonary flow. Systemic oxygen saturation (SaO2) gradually decreased to less than 70%, and a classic left Blalock-Taussig (BT) shunt was constructed at 1 year. During the operation, the ductus arteriosus was left patent, and SaO2 increased to approximately 85%. At 2 years of age, angiography was repeated because of low SaO2, which revealed a closed ductus arteriosus and a narrow underdeveloped right pulmonary artery (PA). Although the left BT shunt was still functioning fully, SaO2 at that time was 49.2%. To increase pulmonary flow and stimulate development of the right PA, a right modified BT shunt was constructed by extending a 6-mm polytetrafluoroethylene tube graft from the right subclavian artery to the right PA just proximal to the superior branch. Postoperatively, SaO2 increased to 80%. At approximately 10 years of age, the patient began to experience recurrent episodes of pneumonia and hemoptysis. A pulmonary perfusion scan at 12 years of age disclosed the absence of perfusion in the left lung. Pulmonary angiography and echo-cardiography revealed pulmonary vein obstruction on the left side. Catheterization showed pressures of 78/60 (mean, 64) mm Hg in the left PA compared to only 15/13 (mean, 14) mm Hg in the right PA. Based on these findings, a diagnosis of unilateral pulmonary vein obstruction was made, and a left pneumonectomy was performed.
Histological examination of the resected specimen showed widespread changes in the small pulmonary arteries and veins. In addition to very severe medial hypertrophy, concentric irregular intimal fibrosis secondary to old arteritis in the small pulmonary arteries had narrowed or completely obstructed many of these vessels. In some arteries, there was accompanying fibrinoid necrosis of the media (the late stage of pulmonary arteritis). Small pulmonary veins or venules showed the most marked intimal fibrous tissue proliferation and medial hypertrophy with resulting luminal narrowing or obliteration. On the other hand, veins larger than 200 µm in diameter appeared to be almost normal, although slight medial thickening was evident. Therefore, the diagnosis was PVOD affecting not only veins approximately 100 µm in diameter but also small pulmonary arteries. The very rare combination of fibrous thickening of venules and old arteritis due to marked medial hypertrophy caused almost total dysfunction of the left lung.
One month after the left pneumonectomy, a central shunt was created to improve the patient’s hypoxemia. One year later, a wedge biopsy of the middle lobe of the right lung was performed to assess the feasibility of performing a Fontan procedure.2 Microscopy showed slight intimal fibrous thickening of the venules, but no other changes in the small pulmonary arteries or veins. The catheterization data at this time yielded a right PA pressure of 13/11 (mean, 12) mm Hg, PA resistance index of 1.1 Wood units x m2, and a Nakata PA index of 380 mm2.m-2. The patient has been scheduled for a Fontan operation.
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DISCUSSION
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The characteristic feature of PVOD is widespread occlusion of small pulmonary veins and venules by fibrosis and intimal proliferation.1 In our patient, small venules less than 100 µm in diameter exhibited proliferation of fibrous tissue and luminal occlusion, which led to destruction of the left lung. Wagenvoort and colleagues1 stated that changes in the pulmonary arteries are much more limited than in the pulmonary veins. In most PVOD patients, the characteristic features of plexogenic pulmonary arteriopathy, such as concentric laminar intimal fibrosis, arteritis, and plexiform lesions, are absent. However, in our patient, the medial thickening of the small pulmonary arteries was extremely severe, and the media had been almost completely destroyed by arteritis. Yamaki and colleagues3 investigated pulmonary arterial changes after BT or central shunts, and reported that medial necrosis or marked hypertrophy due to arteritis did not occur in small pulmonary arteries. The fact that medial hypertrophy of the small pulmonary arteries was evident only in the left lung also suggested that the changes were not caused by the BT shunt. The cause of PVOD and old angitis of the small pulmonary arteries in this case is unclear, but certain hereditary factors such as polysplenia may have contributed.
There have been few reports of histologically proven unilateral PVOD.4 If the lesion in the right lung worsens, it could provide some insight into how PVOD develops in the lung, which in this case appeared normal on chest radiography and angiography. It will be necessary to follow our patient carefully to assess the outcome of the Fontan operation and to determine whether the minor lesions in the venules of the right lung worsen.
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Figure 1. Sections from the destroyed left lung. (A) Transverse section of a small pulmonary artery (100 µm in diameter) showing a late stage of arteritis: severe medial hypertrophy with necrosis and fibrous intimal changes, resulting in almost total occlusion of the lumen (Elastica-Masson stain, original magnification x150). (B) Transverse section of a small pulmonary vein (70 µm in diameter) showing proliferated loose fibrous tissue characteristic of pulmonary veno-occlusive disease (Elastica-Masson stain, original magnification x250).
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Figure 2. Sections from the right lung. (A) Transverse section of a small pulmonary artery (120 µm in diameter) that appears almost normal (Elastica-Masson stain, original magnification x100). (B) Transverse section of a small pulmonary venule (60 µm in diameter) showing slight intimal fibrosis (Elastica-Masson stain, original magnification x250).
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REFERENCES
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- Wagenvoort CA, Wagenvoort N, Takahashi T. Pulmonary veno-occlusive disease: involvement of pulmonary arteries and review of the literature. Hum Pathol
1985;16:1031–41.
- Yamaki S, Ajiki H, Haneda K, Takanashi Y, Ban T, Takahashi T. Pulmonary arterial changes in patients dying after a modified Fontan procedure following pulmonary artery banding. Heart Vessels
1994;9:263–8.[Medline]
- Yamaki S, Nakayama S, Haneda K, Ito T, Yaginuma G, Sadahiro M, et al. Pulmonary vascular disease in shunted and non-shunted patients with tetralogy of Fallot. Jpn J Thorac Cardiovasc Surg
1989;37:62–7.
- Pajewski M, Reif R, Manor H, Starinsky R, Katzir D.Pulmonary veno-occlusive disease in a unilateral hypertransradiant lung. Thorax
1981;36:397–9.[Free Full Text]
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ABSTRACT
INTRODUCTION
