Pulmonary arteriovenous malformations: overview and transcatheter embolotherapy.

Pulmonary AVMs are most commonly seen in patients with HHT, a fascinating multi-system disorder that is all too often underdiagnosed and undertreated. Not only a medical curiosity, HHT is a serious condition that causes substantial morbidity and mortality. Pulmonary AVMs are effectively and safely treated by transcatheter embolotherapy.     

Congenital arteriovenous malformations: tailored embolotherapy

Congenital arteriovenous malformations (AVMs) involving the pelvis or an extremity were occluded in 16 symptomatic patients, who subsequently underwent tailored embolotherapy. An additional 11 patients did not undergo embolization due to unfavorable vascular anatomy or lack of significant symptoms. Permanent occlusive agents including isobutyl cyanoacrylate, particles of polyvinyl alcohol foam, and coils were used to embolize the multiple feeding vessels and, when possible, the nidus of the AVM. All patients experienced dramatic reduction in pain and resolution of ulceration and bleeding, with a mean follow-up period of 41 months. Symptoms recurred in four patients but again resolved with repeat embolization. The authors conclude that selective and repetitive embolization is highly effective in palliation of symptomatic congenital AVMs.     

Long-term outcome of embolotherapy and surgery for high-flow extremity arteriovenous malformations

PURPOSE: To assess the long-term efficacy of embolotherapy in combination with surgery for management of symptomatic high-flow arteriovenous malformations (HFAVMs) of the lower and upper extremities. MATERIALS AND METHODS: Twenty consecutive patients with symptomatic high-flow lower extremity AVMs (LE-AVMs; n = 9) and upper extremity AVMs (UE-AVMs; n = 11) were treated from 1982 to 1999. All nine patients with LE-AVM had pain and seven had ulceration of the skin. All 11 patients with UE-AVM had debilitating pain, seven had weakness of the affected hand, and two had bony erosion. Embolization of the nidus beneath the site of maximum pain or ulceration was performed percutaneously from the femoral artery through coaxially placed microcatheters (n = 18) or surgical cutdown (n = 2). Cyanoacrylate (isobutyl or n-butyl) diluted with iophendylate or ethiodized oil was used in 19 of 20 patients. RESULTS: Follow-up was completed in eight of nine patients with LE-AVM (mean, 8.6 y) and nine of 11 patients with UE-AVM (mean, 7.4 y) after treatment. One patient with localized LE-AVM was functioning well 13 years after embolotherapy and another was functioning well 16 years after undergoing three embolotherapy procedures and two skin grafts. Five of nine patients with LE-AVM required below-the-knee (n = 4) or above-the-knee (n = 1) amputation 1-6 years after technically and clinically successful embolotherapy. All three trifurcation arteries were diffusely involved in HFAVM in patients requiring amputation. Healing of the two amputation sites, involved by AVM at the knee, was excellent after preoperative geniculate artery embolotherapy. All 11 patients with UE-AVM experienced marked symptomatic improvement; seven after embolotherapy alone and the other four after resection of AVM. One complication of digital spasm was reversed by administration of nerve blocks. CONCLUSIONS: LE-AVM with diffuse involvement of all three trifurcation arteries ultimately required amputation because of recurrence of symptoms after technically and clinically successful embolotherapy. Cyanoacrylate embolotherapy alone or in combination with surgical resection of the AVM provided excellent long-term palliation in patients with UE-AVM.     

Pulmonary arteriovenous malformations treated with embolotherapy: helical CT evaluation of long-term effectiveness after 2-21-year follow-up

PURPOSE: To retrospectively evaluate the long-term results of transcatheter embolotherapy of pulmonary arteriovenous malformations (PAVMs) with helical computed tomography (CT). MATERIALS AND METHODS: Neither institutional review board approval nor patient consent was required for this retrospective study. Thirty-eight patients underwent follow-up helical chest CT 2-21 years after successful embolotherapy of 64 PAVMs. Four outcome categories were analyzed on the basis of the PAVM morphologic changes and perfusion findings seen on CT angiograms: successful treatment (marked reduction or disappearance of the aneurysmal sac), partially successful treatment (reduced size of the aneurysmal sac and pulmonary vessels, with feeding artery[ies] less than 3 mm in diameter, deemed too small to be occluded), partially failed treatment (reduced size of the aneurysmal sac and pulmonary vessels, with feeding artery[ies] larger than 3 mm and additional embolotherapy required), and failed treatment (similar size of or interim growth in the aneurysmal sac, with unchanged or enlarged pulmonary vessels). chi(2) or Fisher exact tests were used to analyze categorical variables; Mann-Whitney rank tests were used to analyze continuous variables. P < .05 was considered to indicate statistical significance. RESULTS: Long-term follow-up of the 64 occluded PAVMs revealed successful treatment of 30 (47%), partially successful treatment of 18 (28%), partially failed treatment of two (3%), and failed treatment of 14 (22%) PAVMs. The overall treatment success rate was 75% (47% plus 28%). Delayed recanalization requiring repeat embolotherapy occurred in 12 (19%) cases. No relationship between failed treatment and number of coils deposited in the feeding arteries was found. The frequency of gastrointestinal tract and/or hepatic arteriovenous fistulas at initial diagnosis (P = .01) and/or the interim development of pulmonary hypertension with or without heart failure (P = .01) was significantly higher in patients with at least one PAVM for which embolotherapy failed (n = 9) than in patients who underwent successful or partially successful embolotherapy of all PAVMs (n = 29). CONCLUSION: Long-term CT follow-up of initially successfully treated PAVMs revealed successful embolotherapy of 75% and partially or completely failed embolotherapy of 25% of PAVMs.     

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.     

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.     

Ethanol embolotherapy of pelvic arteriovenous malformations: an initial experience.

OBJECTIVE: We retrospectively assessed the results of performing ethanol embolization for pelvis arteriovenous malformations (AVMs). MATERIALS AND METHODS: During the past 10 years, eight patients (8 females, age range: 27-52 years) with AVMs in the pelvic wall (n = 3) and uterus (n = 5) underwent staged ethanol embolizations (range: 1-5, mean: 2.5) under general anesthesia. Ethanol embolization was performed by the use of the transcatheter and/or direct puncture techniques. Clinical follow-up was performed for all of the patients, and imaging follow-up was available for seven patients. The therapeutic outcomes were established by evaluating the clinical outcome of the signs and symptoms, as well as the degree of devascularization observed on post-procedural angiography. RESULTS: During the 20 sessions of ethanol embolization, the solitary transarterial approach was used 14 times, the transvenous approach was used three times and direct puncture was used once. For two patients, the transarterial and transvenous or direct puncture approaches were used together in one session. For four patients, ethanol and coils were used as embolic agents, and n-butyl cyanoacrylate (NBCA) and ethanol were used in one patient. Seven (88%) of eight patients were cured of their AVMs and one patient (12%) displayed improvement. Major complications were seen in two patients (25%). CONCLUSION: Ethanol embolization is effective for the treatment of pelvic arteriovenous malformations, though there is a chance of a major complication.     

Angioarchitecture of pulmonary arteriovenous malformations: an important consideration before embolotherapy

Seventeen patients with 91 pulmonary arteriovenous malformations were evaluated by superselective angiography. Seventy-two (79%) of the malformations consisted of a simple type characterized by a single feeding artery draining into a bulbous, nonseptated aneurysmal communication with a single draining vein. The other 19 (21%) were complex, consisting of two or more pulmonary artery branches communicating with a bulbous septated aneurysmal part with two or more draining veins. Two patients had diffuse pulmonary arteriovenous malformations confined to multiple lobes of the lung. Balloon embolotherapy was effective in permanently obliterating the malformations in 14 patients treated. Therapy provided a sustained rise in arterial PO2 in the sitting position from a mean value of 44 mm Hg before occlusion to 65 mm Hg after occlusion. In three patients the process was too diffuse and/or the malformations too large for therapy to be effective. Complex pulmonary arteriovenous malformations required occlusion of all feeding arteries. Balloon embolotherapy provided an effective treatment for pulmonary arteriovenous malformations regardless of anatomic type.     

应用Onyx栓塞治疗脑动静脉畸形的护理

目的:探讨应用Onyx栓塞治疗脑动静脉畸形的护理.方法:回顾性分析44例脑动静脉畸形患者的术前、术后临床资料并总结护理经验.结果:本组完全栓塞4例,栓塞80%以上7例,栓塞50%～80% 21例,栓塞50%以下12例.栓塞术后发生粘管1例,出现肢体偏瘫2例,经解痉、促进微循环供血等治疗明显好转,脑内出血1例,急症开颅清除血肿,肢体留有偏瘫.其余病例无严重并发症.结论:术前充分准备,术后精心护理对保证栓塞的疗效具有重要的意义.     

Pulmonary arteriovenous malformations: embolotherapy with superselective coaxial catheter placement and filling of venous sac with Guglielmi detachable coils

PURPOSE: To determine whether criteria for screening patients with sickle cell anemia for stroke established with a nonimaging transcranial Doppler ultrasonographic (US) technique are applicable to studies performed with a transcranial Doppler US imaging technique. MATERIALS AND METHODS: One hundred sixty-eight examinations in 66 children were performed for sickle cell stroke screening. Children were examined with nonimaging and imaging transcranial Doppler US techniques on the same day, for a total of 84 paired examinations. The time-averaged maximum mean velocity (V(mean)) and resistive index (RI) were calculated in the middle cerebral arteries, bifurcations of the distal internal carotid arteries, distal internal carotid arteries, anterior cerebral arteries, posterior cerebral arteries, and basilar arteries. The maximum systolic velocity (V(max)) was evaluated in the distal internal carotid arteries and middle cerebral arteries. V(mean), V(max), and RI measurements were subjected to repeated-measures multivariate analysis of covariance, and the Pearson product moment correlation was used for middle cerebral artery velocity, age, and hemoglobin. RESULTS: V(mean) measurements obtained with nonimaging and imaging techniques varied substantially for the bifurcation of the distal internal carotid artery, the posterior cerebral artery, and the basilar artery. Substantial differences were found in RIs for every vessel. Examination time was shorter with the nonimaging technique. CONCLUSION: V(mean) measurements in the middle cerebral artery, distal internal carotid artery, and anterior cerebral artery did not vary substantially between nonimaging and imaging transcranial Doppler US. RI data did not yield comparable measurements.     

The pathology of encephalic arteriovenous malformations treated by prior embolotherapy

Summary A pathologic study was undertaken of seven encephalic arteriovenous malformations, including five resected from one to seven days after balloon embolization, one resected 10 days after embolization with polyvinyl alcohol foam (PVA), and a large mesencephalic AVM in a patient who died eight weeks after a series of embolization procedures with PVA and silicone spheres. AVM's resected 6–7 days following balloon embolization showed focal mural and adventitial inflammatory infiltrates and parenchymal (i.e. non-vascular) necrosis of a large portion of one AVM. The AVM examined 7 days post-balloon embolization showed an intraluminal thrombus containing refractile particles surrounded by foreign body giant cells (FBGC's). The AVM removed 10 days after PVA embolotherapy showed mural and perivascular necrosis with infiltration by polymorphonuclear leukocytes. The single autopsy case showed FBGC's surrounding residual PVA, refractile particles deep within vascular walls, and marked mural thickening of AVM channel walls, changes that may represent a response to previous angionecrosis and inflammation at the time of embolization. These findings, the pathogenesis of which is discussed in detail, may help to explain some of the rare complications of iatrogenic embolotherapy with these materials, as well as providing evidence for the basis of their efficacy.Presented in part at the 63rd Annual meeting of the American Association of Neuropathologists, Seattle, Washington, June, 1987     

脑动静脉畸形介入治疗并发症的观察与护理

目的：探讨脑动静脉畸形（AVM）栓塞治疗并发症的观察与护理。方法：回顾性分析152例脑动静脉畸形介入治疗术中并发症的发生,总结护理观察经验。结果：AVM位于额顶叶87例、顶枕叶34例、颞顶叶17例、基底节区7例、小脑半球7例。畸形团直径小于3cm的56例,3~6cm的72例,大于6cm的24例。注射Onyx栓塞脑动静脉畸形,畸形团完全栓塞42例,畸形团栓塞80%以上62例,畸形团栓塞50%~80%34例,畸形团栓塞50%以下14例。术中并发症：2例栓塞术中发生粘管;8例栓塞术后出现肢体偏瘫,由于护理观察及时,经解痉、降低颅内压、促进微循环供血等治疗好转;1例脑出血急症开颅清除血肿,肢体留有偏瘫。其余病例无严重并发症。结论：术前充分准备,术中预见性观察与处理对保证栓塞的疗效,减少并发症的发生具有重要的意义。     

The pathology of arteriovenous malformations of the brain treated by embolotherapy

Light microscopic and immunohistochemical examination was undertaken of intracranial arteriovenous malformations (AVMs) surgically resected from 18 patients, each of whom had undergone preoperative angiographic embolization with multiple agents. Distinct patterns of tissue reaction to these agents were noted, even when more than one substance was present in a vascular lumen. Avitene produced the mildest tissue response but resulted in relatively early endothelialization and recanalization. Cyanoacrylates were longer-lasting but associated with more acute and chronic (including granulomatous) inflammation and vessel wall changes. Polyvinyl alcohol foam/ethanol mixture had intermediate properties. Endothelial proliferation over embolization material was confirmed using immunohistochemical application of an antibody to cell proliferation-specific proteins. The significance of these findings for combined endovascular and surgical treatment of cerebral vascular malformations is discussed.     

真丝线段栓塞脑动静脉畸形56例

目的:探讨脑动静脉畸形(AVM)的治疗手段。方法:对56例经真丝线段栓塞的AVM进行分析,按S-M分级Ⅰ级10例,Ⅱ级18例,Ⅲ级19例,Ⅳ级9例。单纯行真丝线段栓塞31例,真丝线段栓塞+γ-刀治疗15例,真丝线段栓塞+手术切除10例。所有患者均经1~6年随访。结果:单纯行真丝线段栓塞病灶消失10例,病灶缩小50%以上14例。真丝线段栓塞+γ-刀治疗病灶消失7例,病灶缩小50%以上3例,5例病灶缩小50%以下。真丝线段栓塞+手术切除病灶消失7例。全组无死亡,1例留有不完全性偏瘫、失语。结论:真丝线段栓塞AVM尤其是位于脑重要功能区的AVM仍然是治疗脑AVM有效的主要手段,真丝线段栓塞结合手术切除或γ-刀治疗脑AVM可提高治疗效果。     

Acquired uterine vascular malformations: radiological and clinical outcome after transcatheter embolotherapy

The purpose of this retrospective study is to assess the radiological and clinical outcome of transcatheter embolization of acquired uterine vascular malformations in patients presenting with secondary postpartum or postabortion vaginal hemorrhage. In a cohort of 17 patients (mean age: 29.7 years; standard deviation: 4.23; range: 25–38 years) 18 embolization procedures were performed. Angiography demonstrated a uterine parenchymal hyperemia with normal drainage into the large pelvic veins (low-flow uterine vascular malformation) in 83% (n=15) or a direct arteriovenous fistula (high-flow uterine vascular malformation) in 17% (n=3). Clinically, in all patients the bleeding stopped after embolization but in 1 patient early recurrence of hemorrhage occurred and was treated by hysterectomy. Pathological analysis revealed a choriocarcinoma. During follow-up (mean time period: 18.8 months; range: 1–36 months) 6 patients became pregnant and delivered a healthy child. Transcatheter embolization of the uterine arteries, using microparticles, is safe and highly effective in the treatment of a bleeding acquired uterine vascular malformation. In case of clinical failure, an underlying neoplastic disease should be considered. Future pregnancy is still possible after embolization.     

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.