Coil embolization of pulmonary arteriovenous malformations

Pulmonary arteriovenous malformations (PAVMs) are uncommon lesions that can be treated by surgery or interventional radiology. Forty-four PAVMs in 11 patients were occluded by transcatheter coil embolization with only one symptomatic complication, deep venous thrombosis, attributable to the procedure. There was a significant improvement in symptoms and a reduction in pulmonary AV shunting in the 9 patients in whom embolization of all visible discrete lesions was successfully completed. Coil embolization is an effective alternative to other methods of treating PAVMs.     

肺动静脉畸形的CT表现

肺动静脉畸形(Pulmonary Arteriovenous Malformation,PAVM)在临床上较为罕见,因其可能引起严重的临床症状诸如脑梗死、致命性大咯血等[1],故及时准确地诊断就显得极为重要.PAVM的CT诊断鲜有文献报道,笔者搜集经肺动脉造影证实的3例PAVM患者,分析其CT表现并复习相关文献,旨在提高PAVM的CT诊断水平.     

Interventional treatment of pulmonary arteriovenous malformations

Pulmonary arteriovenous malformations (PAVM) are congenital vascular communications in the lungs. They act as right to left shunts so that the blood running through these malformations is not oxygenated or filtered. These patients are typically hypoxaemic with exercise intolerance and are at high risk of paradoxical emboli to the brain and other organs. These malformations are most commonly seen in hereditary haemorrhagic telangiectasia (HHT) (Mb. Osler-Weber-Rendu syndrome). Nowadays, the generally accepted treatment strategy of first choice is embolization of the afferent arteries to the arteriovenous malformations. It is a minimally invasive procedure and at the same time a lung preserving treatment with a very high technical success, high effectiveness and low morbidity and mortality. Embolization prevents cerebral stroke and abscess as well as pulmonary haemorrhage and further raises the functional level. Embolization is a well-established method of treating PAVM, with a significant effect on oxygenation of the blood. Screening for PAVM in patients at risk is recommended, especially in patients with HHT.     

Reperfusion of pulmonary arteriovenous malformations after embolotherapy

PURPOSE: To describe the mechanisms and risk factors associated with reperfusion of successfully treated pulmonary arteriovenous malformations (PAVMs) after embolotherapy. MATERIALS AND METHODS: Among 112 consecutive patients with PAVMs treated by embolotherapy, 19 patients were identified who had 33 angiographically confirmed reperfused PAVMs. A retrospective analysis of computed tomography (CT) and angiography was performed in patients with documented reperfused PAVMs in which reperfused PAVMs were compared with nonreperfused PAVMs. CT images were examined for persistence of the aneurysm and/or draining vein after initial embolotherapy and correlated with angiography to determine the mechanism of reperfusion. PAVM and embolic agent characteristics (eg, feeding artery size and number; PAVM location; coil size, number, and location) were evaluated for association with reperfusion. The outcomes of repeat embolotherapy for reperfused PAVMs were evaluated. RESULTS: The PAVM aneurysm and/or draining vein persisted on CT after initial embolotherapy in all reperfused PAVMs and resolved in all nonreperfused PAVMs (in patients with nondiffuse PAVMs). Recanalization was the mechanism of reperfusion in 88%. Reperfusion was associated with the use of a single coil (P < .0001), oversized coils (P < .0001), coil placement more than 1 cm from the aneurysm (P < .0001), and increased feeding artery size (P < .001). Repeat embolotherapy for reperfused PAVMs was technically successful in 94% of cases. In the remaining 6% of cases, insufficient feeding artery length prevented safe repeat treatment. After a mean follow-up of 41 months, 42% of reperfused PAVMs in our series have been successfully treated again and occluded. CONCLUSIONS: Recanalization is the most common mechanism of PAVM reperfusion. Increased feeding artery diameter, low number of coils, use of oversized coils, and proximal coil placement within the feeding artery are associated with reperfusion. Distal coil placement facilitates repeat embolization if reperfusion occurs.     

Diagnosis and endovascular management of pulmonary arteriovenous malformations

Pulmonary arteriovenous malformations (PAVM) are abnormal communication of a branch of the pulmonary artery and pulmonary vein circumventing the intervening pulmonary capillaries. This results in a right-to-left (R-L) shunt and its related manifestations, which include hampered gas exchange leading to hypoxaemia, dyspnoea, paradoxical emboli leading to stroke, cerebral abscess, myocardial infarction and pulmonary haemorrhage due to rupture of the PAVM. Endovascular transcatheter embolization of the feeding vessels with coils or occlusion devices is the current standard care of treatment and preferred treatment modality. The articles aim to provide insights into the current trends in diagnosis, the current recommendations, approach and management options for patients with PAVM.     

Bioptome-assisted coil closure of large pulmonary arteriovenous malformations

Large pulmonary arteriovenous malformations (AVMs) with feeding vessels larger than 5 mm cause significant right-to-left shunt resulting in cyanosis and need to be occluded as soon as they are diagnosed. Occlusion of such AVMs by simultaneous delivery of multiple coils was attempted in five patients and was successful in completely occluding the AVM in four of them. One patient had transient chest pain during the procedure, presumably as a result of coronary air embolism. A bioptome was used to hold the multiple coils together for optimal deployment and controlled release of the coils.     

螺旋CT血管成像诊断肺动静脉畸形的价值

目的:探讨多层螺旋CT肺血管成像在肺动静脉畸形(PAVM)中的诊断价值。方法:回顾性分析7例PAVM的多层螺旋CT三维肺血管成像的影像表现,1例为多发,6例单发。2例经手术证实,5例经其他影像学检查方法及随访证实。结果:7例PAVM均清晰显示瘤体形态、大小、位置,以及供血动脉、引流静脉数目、走行、直径。单纯型4例,复杂型2例,弥漫型1例。结论:多层螺旋CT肺血管成像可以明确PAVM的瘤体、供血动脉、引流静脉的空间关系和解剖细节,可作为PAVM的首选检查和随访方法。     

Pulmonary venous anomalies causing misdiagnosis of pulmonary arteriovenous malformations

PurposeTo investigate pulmonary venous anomaly as a cause of pulmonary arteriovenous malformation (PAVM) misdiagnosis.Materials and methodsWe reviewed adult patients within a 7.5-year period with CT scans initially diagnosed with PAVM and subsequent conventional pulmonary angiograms.ResultsPulmonary arteriography showed no PAVM on arterial phase for 10 out of 99 patients, comprising the misdiagnosed group. Four misdiagnosed patients had pulmonary venous anomalies and six had nodular lesions on CT.ConclusionPulmonary venous anomalies are vascular mimics of PAVMs that may lead to misdiagnosis. Optimal CT technique and careful imaging review are necessary to minimize inappropriate invasive angiography.     

Occlusion of pulmonary arteriovenous malformations by use of vascular plug

Pulmonary arteriovenous malformations are commonly treated by embolization with coils or balloons to prevent cerebral complications and to raise the oxygenation of the blood. The Amplatzer vascular plug is a new occlusive device made of a self-expanding cylindrical nitinol mesh. It is fast and safe to position, and can be repositioned before final delivery. It is especially suited for embolization of large high-flow vessels as in pulmonary arteriovenous malformations with big feeding arteries. Two cases of successful use of the new device for treatment of large pulmonary arteriovenous malformations are described.     

Diagnosis and quantitation of pulmonary arteriovenous malformations by factor analysis

The diagnosis of a pulmonary arteriovenous malformation (AVM) was made by performing a computer-assisted first-pass cardiopulmonary imaging procedure using Tc-99m pertechnetate and processing the image information using factor analysis. This analytical technique is capable of separating partially overlapping structures by automatically extracting factors with different temporal behavior (time-activity curves) which correspond to functional areas without anatomic constraint. This procedure was accomplished successfully despite the presence of four-chamber enlargement, mitral stenosis and regurgitation, tricuspid regurgitation, chronic obstructive pulmonary disease and pulmonary hypertension. The magnitude of the right-to-left shunt resulting from the AVM was quantitated using both the factor analysis data and an independent Tc-99m MAA computer-assisted imaging procedure. Both methods gave comparable values.     

Clinical and anatomic outcomes after embolotherapy of pulmonary arteriovenous malformations

PURPOSE: To assess long-term clinical and imaging results of technically successful pulmonary arteriovenous malformation (AVM) embolization. MATERIALS AND METHODS: One hundred fifty-five patients with pulmonary AVMs underwent embolization during a period of 3 years. Recommended follow-up included clinical assessment, helical computed tomography, and physiologic evaluation within 1 year and then every 5 years. RESULTS: Hereditary hemorrhagic telangiectasia was present in 148 patients (95%). Four hundred fifteen pulmonary AVMs were occluded during 205 procedures. Clinical follow-up was available in all patients over 3-7 years and imaging follow-up was available in 144 patients (393 lesions) over 1-7 years (mean, 2.9 y). Problems related to pulmonary AVMs occurred in 35 patients (23%) at 42 time points: 22 patients with 23 symptomatic events and 17 patients with 19 asymptomatic events. Symptoms resulted from growth of nonembolized pulmonary AVMs (n = 19), residual embolized pulmonary AVMs (n = 5), or both (n = 2). Symptoms consisted of respiratory manifestations (n = 13), cerebral ischemia (n = 4), brain abscess (n = 5), hemoptysis (n = 3), and seizure (n = 1). Imaging showed pulmonary AVM involution in 97% of embolized lesions and 11 residual lesions (2.8%) in 10 patients (6.9%). These were caused by recanalization (n = 7), presence of an accessory feeding artery (n = 1), pulmonary collateral vessels (n = 1), and bronchial collateral vessels (n = 2). CT detected 10 of the 11 residual lesions. Imaging detected 97 previously small pulmonary AVMs that had enlarged to a significant size in 28 patients (18%), 15 of whom were symptomatic and 13 of whom were asymptomatic. CONCLUSIONS: Clinical and anatomic evaluation after pulmonary AVM embolization is important to detect persistent or reperfused lesions and enlarging lesions, with the latter more common. Patients with persistent, reperfused, or enlarging lesions often have symptoms, but a significant minority of patients are asymptomatic. More frequent assessment may improve detection before the onset of symptoms.     

Pulmonary scintigraphy in a patient with multiple pulmonary arteriovenous malformations and pulmonary embolism

The scintigraphic findings in a patient with multiple pulmonary arteriovenous malformations (AVMs) complicated by superimposed pulmonary embolism are reported. Although pulmonary AVMs may cause small subsegmental scintigraphic abnormalities, the demonstration of perfusion defects which are segmental or larger should strongly suggest the presence of superimposed pulmonary embolism in a patient with multiple pulmonary AVMs.     

Brain arteriovenous malformations

An arteriovenous malformation (AVM) is a particular abnormality of blood vessels. Brain AVMs are congenital, but symptoms usually do not appear until the second decade of life - if at all. The most common presenting symptom is a brain hemorrhage, but other possible symptoms include neurological deficits, seizures and headaches. Until recently, the gold standard for diagnosing AVM was conventional angiography. However, computed tomography and magnetic resonance angiography are now the first-line diagnostic tools for AVMs. This article reviews the presenting symptoms, diagnostic procedures and treatment options for brain AVMs, including embolization, micro-surgery and radiosurgery. This article is a Directed Reading. Your access to Directed Reading quizzes for continuing education credit is determined by your CE preference. For access to other quizzes, go to www.asrt.org/store.     

Embolotherapy of pulmonary arteriovenous malformations: long-term results in 112 patients

PURPOSE: To evaluate the long-term results of embolotherapy of pulmonary arteriovenous malformations (PAVMs) in a large group of patients. MATERIALS AND METHODS: Between July 1988 and August 2001, 134 consecutive patients underwent embolotherapy of PAVMs with feeding arteries larger than 3 mm or that had previously caused bleeding or systemic complications. The mean follow-up was 62.2 months. The primary endpoints of the study were the efficacy of embolotherapy, decrease in right-to-left shunt, and increase in partial arterial oxygen pressure (PaO(2)); the secondary endpoint was the prevalence of complications. Standard follow-up consisted of yearly history, chest radiography, and arterial blood gas measurement. RESULTS: Follow-up was available in 112 patients. Initially, 296 PAVMs were embolized in these patients. Nineteen patients (17%) underwent a second procedure and four patients underwent a third procedure because of recanalization of originally occluded feeding arteries (25 PAVMs, 8%) or interval enlargement of untreated PAVMs (53 PAVMs). In total, 349 PAVMs were embolized in 157 sessions. The mean diameter of occluded vessels was 4.7 mm. The long-term outcomes of embolotherapy were successful in 83% of patients overall and in 96% of patients in whom all angiographically visible PAVMs were embolized. Recanalization occurred in 12 of 16 patients who underwent repeat treatment because of enlargement of nonembolized PAVMs. Postprocedural pleurisy occurred after 14 of 157 sessions (9%). Periprocedural complications occurred in 12 sessions (8%) and included migration of an embolic device, transient ischemic attack (TIA), angina pectoris, and early cerebral infarction after embolization. Three patients experienced TIA and two patients experienced a cerebral abscess during follow-up after embolotherapy. CONCLUSIONS: Embolotherapy of PAVMs is efficacious and durable in the majority of patients. Patients should remain under regular review because recanalization of PAVMs or enlargement of untreated PAVMs can occur years after treatment.     

Reperfusion of pulmonary arteriovenous malformations after successful embolotherapy with vascular plugs

Amplatzer vascular plugs (AVPs) are among the embolic agents currently used for occlusion of pulmonary arteriovenous malformations (PAVMs). The authors encountered a patient with multiple PAVMs who developed spontaneous reperfusion of two PAVMs within 7 weeks of initially successful embolization with AVPs. Reperfused PAVMs were effectively occluded by coils deposited proximal to the vascular plugs. AVPs do not provide consistent long-term occlusion of the PAVMs. Deposition of coils proximal to the AVP may decrease the chance of PAVM reperfusion after the embolization.