Asian Cardiovasc Thorac Ann 2000;8:369-371
© 2000 Asia Publishing EXchange Pte Ltd
Pulmonary Arteriovenous Malformation Complicated by Cerebral Infarction
Öztekin Oto, MD,
Kivanç Metin, MD,
Nejat Sariosmano
lu, MD,
Eyüp Hazan, MD,
Erdem Silistreli, MD
Department of Thoracic and Cardiovascular Surgery
Faculty of Medicine
Dokuz Eylül University
 zmir, Turkey
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For reprint information contact: Kivanç Metin, MD Tel: 90 232 277 2165 Fax: 90 232 277 2165 email: kmetin{at}yahoo.com Mithatpa a Cad. No. 653/3, zmir 35280, Turkey.
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Abstract
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A 45-year-old epileptic female with fatigue, swollen legs, and numbness of the lower extremities, had radiological findings of increased density in the lower zone of the right lung and a pattern of chronic cerebral ischemia in the territory of the left internal carotid artery. A pulmonary arteriovenous malformation was demonstrated by angiography. A right lower lobectomy was performed successfully.
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Introduction
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A pulmonary arteriovenous malformation (PAVM) is an unusual congenital anomaly that may be a very small connection or a large complex structure.1–4 The amount of right-to-left shunting influences the clinical status. Dyspnea is the major symptom, chronic hypoxemia, secondary polycythemia, and paradoxical emboli may also be present.5,6 When diagnosed, radical treatment of a PAVM is recommended, even in asymptomatic cases, because of the high risk of complications.1,2,5,6
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Case Report
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A 45-year-old female presented with fatigue, headache, swollen legs, and numbness in her lower extremities. She was conscious and her general condition was good. She had a history of epilepsy and right-sided hemiparesis for 30 years. Moderate tachypnea, clubbing, and a continuous murmur below the right scapular area on chest auscultation were noted. All peripheral pulses were palpable and there were no signs of heart failure. Laboratory tests were within normal limits, except for a slightly depressed hemoglobin level (112 g•L–1) in spite of her hypoxemia. A plain chest radiograph showed increased density in the lower zone of the right lung at the supradiaphragmatic subpleural region. At the same location, a soft-tissue lesion of 4-cm in diameter with some calcification and lobules, which was limited by pleura on the dorsal side, was detected on computed tomography (CT) of the thorax (Figure 1
). Because of the tachypnea, hypoxemia, and swollen and aching legs, Doppler scanning of the deep veins of the lower extremities and a ventilation-perfusion scan of the lungs were also performed. The radio-pharmaceutical media were visualized in great amounts in the liver on scintigraphic examination and this gave a clue to the presence of an arteriovenous malformation. The image on Doppler ultrasound was similar to that of chronic clotting on the vessel wall and blood flow was decreased in the distal one-third portions of the right femoral and popliteal veins. The etiology of the epilepsy was unclear and cerebral CT and magnetic resonance imaging were also performed. There were chronic ischemic patterns in the left occipitoparietal temporal lobe of the brain, which is the territory of the left internal carotid artery. Echocardiography showed minimal pericardial fluid and aortic insufficiency, inconsistent with the auscultation findings. A PAVM was diagnosed and confirmed by intravenous digital subtraction angiography. The PAVM was visible in the lower lobe of the right lung (Figure 2).
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Figure 1. Computed tomography image showing the pulmonary arteriovenous malformation in the right lung.
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The internal diameter of the artery feeding the PAVM was larger than 3 mm. Poor results of balloon or coil em-bolization of such large connections have been reported previously so a transcatheter approach was rejected.1 A right posterolateral thoracotomy was performed. There was a visible pulsation and a thrill in the lower lobe, which were in agreement with the CT and angiographic findings. A right lower lobectomy was carried out and no operative complications were encountered. The post-operative course was satisfactory and the patient was discharged on the 6th postoperative day without any signs of hypoxemia. Pathological examination showed a large arteriovenous malformation in the lower lobe, which was supplied by one artery and drained by several small veins.
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Discussion
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PAVM is unusual but not a rare congenital anomaly.4 It is often associated with hereditary hemorrhagic telan-giectasia (HHT), a systemic fibrovascular dysplasia with autosomal dominant transmission.1,4,6 The association of PAVM with HHT is almost 80% and there are usually multiple lesions, but PAVM without HHT is often a single lesion.3,5 The amount of right-to-left shunting determines the degree of hypoxemia, decreased exercise capacity, dyspnea, cyanosis, and often, secondary polycythe-mia.1,2,5,6 There can be severe and fatal complications such as bleeding from the abnormal vessels, causing hemoptysis and hemothorax, and paradoxical emboli from the venous system, mostly to the brain, due to bypassing the capillary filter of the lung. More than half of the patients with PAVM report a history of stroke or transient ischemic attack.1,5 Cerebral abscesses occur in 20% of patients as a result of septic emboli.1,5 Emboli to other sites are very rare.1 Because of these potentially fatal complications, screening of the family members of such patients is essential.3–5
The route to diagnosis begins with suspicion at the initial examination of a patient with signs of hypoxemia (tachypnea, cyanosis, fatigue) and the presence of a continuous murmur on auscultation. Plain chest radio-graphs show abnormalities in approximately 98% of patients, such as peripheral non-calcified lesions connected by blood vessels to the hilum, or coin lesions.2 PAVMs appear on CT as homogenous circumscribed noncalcified nodules. CT has a sensitivity of up to 98% in diagnosing PAVM, depending on the experience of the radiologist.2 Angiography remains the definitive imaging technique for confirmation of PAVM.2 Both techniques were used to confirm the diagnosis in this case. Pulmonary hypertension may coexist with PAVM and angiography with catheterization is superior to CT in detecting this condition. It can also be suspected if the central pulmonary arteries are enlarged on CT images.2 Detection of pulmonary hypertension is considered essential because transcatheter occlusion or surgical removal of low-resistance shunts may increase pulmonary arterial pressure in the posttreatment period.2,3
PAVMs must be treated even if they are asymptomatic, because of the progressive nature of the disease.1,3–6 Balloon or coil embolization of these anomalies has superseded surgical therapy, due to recent improvements in catheter technology, although long-term results are unclear.1,3–6 Patients must be followed up periodically with CT to evaluate the effectiveness of treatment and to detect potential complications such as lung infarction and pleuritis.2,4
This case demonstrates that PAVM should be treated immediately before a severe complication appears. Our patient suffered a cerebral infarction, possibly due to paradoxical venous embolization from the lower extremities. This might have been avoided if she had been diagnosed and treated earlier. Because of the correlation between PAVM and HHT, the need to investigate the family members of such patients must be emphasized.
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References
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Watanabe N, Munakata Y, Ogiwara M, Miyatake M, Nakagawa F, Hirayama J. A case of pulmonary arteriovenous malformation in a patient with brain abscess successfully treated with video-assisted thoracoscopic surgery. Chest 1995;108:1724–7.[Abstract/Free Full Text]
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Abstract
Introduction
