Treatment Outcomes of Embolization for Peripheral Arteriovenous Malformations

PurposeTo evaluate treatment outcomes of embolization for peripheral arteriovenous malformations (AVMs) in a tertiary referral center where ethanol is the primary agent of choice.MethodsA retrospective study was performed of 93 patients (median age, 31 years; range, 2–66 years) with peripheral AVMs treated with embolization (n = 442; median, 2 per patient; range, 1–82) between January 2010 and July 2016. Ethanol was used in most cases (n = 428; 97%). AVMs were classified as type I (n = 3), type II (n = 57), type IIIa (n = 5), type IIIb (n = 15), and type IV (n = 13) according to the Yakes classification system. Effectiveness of embolization was based on AVM devascularization on angiography: 100% (total), 90%–99% (near-total), 70%–90% (substantial), 30%–70% (partial), and 0%–30% (failure). Complications were graded according to the Society of Interventional Radiology classification.ResultsIn 69% of patients, 70%–100% devascularization was achieved. Total and near-total occlusion of the nidus were more often achieved in AVMs of types I and IIIa (both 100%) than in AVMs of types II, IIIb, and IV (56%, 67%, and 39%, respectively; P = .019). A total of 109 complications were identified: 101 minor (22.9%) and 8 major (1.8%). Major complications included wounds (n = 5), false aneurysm (n = 1), finger contracture (n = 1), and severe pain (n = 1) requiring therapy. The patient complication risk was significantly affected by the number of procedures (relative risk = 2.0; P < .001). Age, AVM location, and angioarchitecture type did not significantly affect complication risk.ConclusionsAVM embolization resulted in 70%–100% devascularization in 69% of patients, with few major complications. This study indicates that the type of AVM angioarchitecture affects the number of procedures needed and the achievability of AVM devascularization.     

Absolute Ethanol Embolization of Lip Arteriovenous Malformations: Observational Results from 10 Years of Experience

PurposeTo evaluate the safety and efficacy of ethanol embolization of lip arteriovenous malformations (AVMs).Materials and MethodsSeventy-six patients with lip AVMs were treated with 173 ethanol embolization procedures. Lip AVMs were treated with direct puncture alone in 21 patients (35 procedures, 20.2%), transarterial embolization alone in 13 patients (18 procedures, 10.4 %), and a combination of both in 60 patients (120 procedures, 69.3%). Adjunctive surgical resection was performed after embolization for cosmetic purposes based on the patient’s request, including patient preference, functional impairment, and skin necrosis. The mean duration of follow-up was 30.9 months ± 27.6. The follow-up included clinic visits and telephonic questionnaires to evaluate the clinical signs and symptoms of AVMs as well as quality of life measures.ResultsOf 76 patients, 51 showed 100% devascularization of AVMs, as determined using arteriography, followed by 23 with 76%–99% devascularization and 2 with 50%–75% devascularization. Of the 76 patients, 40 achieved complete symptom relief and 25 achieved major improvements in cosmetic deformity after embolization. Additionally, 54 patients achieved satisfactory function and aesthetic improvement with ethanol embolotherapy alone, whereas 22 achieved similar outcomes with a combination of ethanol embolotherapy and surgical intervention. Thirty-three adverse events (including 1 major) were documented.ConclusionsEthanol embolization of lip AVMs, as a mainstay, is efficacious in managing these lesions, with acceptable complications. Surgical resection after embolization may improve function and cosmesis in a subset of patients.     

Safety and Effectiveness of Ethylene Vinyl Alcohol Copolymer Embolization of Peripheral High-Flow Arteriovenous Malformations: Results of a Prospective Study

PurposeTo prospectively evaluate the efficacy and safety of a new ethylene vinyl alcohol (EVOH) copolymer–based embolic agent in the treatment of symptomatic peripheral arteriovenous malformations (AVMs).Materials and MethodsThis prospective single-center study evaluated EVOH embolization with 3 different formulations of EVOH (Squid Peri 12 cP, 18 cP, and 34 cP; BALT Germany GmbH, Düsseldorf, Germany) in patients with symptomatic AVMs. Between April 2018 and October 2019, 36 embolization procedures in 21 patients (3 males and 18 females; mean age, 34.7 years) were performed (inclusion criteria: symptomatic peripheral AVM, ≥14 years of age, and elective embolization). Symptoms, technical aspects (transarterial, transvenous, or percutaneous approach; plug or balloon occlusion), clinical and technical success (defined as the improvement of symptoms and complete angiographic eradication of the AVM nidus), adverse events, and short-term outcomes were assessed.ResultsThe mean volume of the embolic agent used per session was 3.4 mL of EVOH 34 cP (standard deviation [SD], ± 5.4), 6.2 mL ± 8.1 of EVOH 18 cP, and 4.6 mL ± 10.1 of EVOH 12 cP. Angiographic success was achieved in 18 patients (85.7%). The mean follow-up was 190 days (range, 90–538 days; median, 182 days). In the follow-up assessment, findings of magnetic resonance imaging showed that 19 patients (90.5%) had a persistent state of devascularization compared with postinterventional angiography. Amelioration or complete elimination of pain was achieved in 90.0% of the patients. One patient experienced a major adverse event; minor adverse events developed in 2 patients.ConclusionsIn this study, EVOH appeared to be a safe and effective embolic agent in peripheral AVMs and had a low rate of adverse events in a limited number of patients.     

Comparison of Feeding-Artery-Only versus Nidus-Plus-Feeding-Artery Embolization of Pulmonary Arteriovenous Malformations

PurposeTo compare coil embolotherapy outcomes of feeding-artery-only versus nidus-plus-feeding-artery technique for treating pulmonary arteriovenous malformations (PAVMs).Materials and MethodsA total of 219 treatment-naïve PAVMs embolized in 90 patients at a single center from 2008 to 2018 met inclusion criteria for retrospective evaluation. Of the patients, 87% had a diagnosis of hereditary hemorrhagic telangiectasia (HHT). Feeding artery (FA) diameters ≥2 mm were treated. Coil embolization techniques were classified on the basis of embolic deployment zone: (i) distal feeding artery (DFA) technique (coil-to-nidus distance ≤ 1 cm) or (ii) nidus plus feeding artery (NiFA) technique. Successful embolization predictors were assessed using a multivariate linear regression model with input from patient- and PAVM-specific variables.ResultsTreatment success was achieved in 192 of 219 PAVMs (87.7%) over a mean follow-up period of 19 months. Statistically significant predictors of success in the linear regression model included simple angioarchitecture, NiFA embolization technique, and shorter follow-up duration. Stratified by technique, success rates were 99 of 105 (94.3%) and 93 of 114 (81.6%) PAVMs for NiFA and DFA, respectively (P = .007). On average, NiFA-embolized PAVMs had a larger FA diameter (3.6 mm vs 2.7 mm, P < .001) and comprised more complex PAVMs (48% vs 22%, P < .001) than DFA. Treatment success was not significantly associated with sac size or FA diameter.ConclusionsCoil embolization of both the nidus and FA was associated with a higher persistent occlusion rate than FA embolization alone.     

Endovascular Treatment of Arteriovenous Malformations of the Head and Neck: Focus on the Yakes Classification and Outcomes

PurposeTo evaluate endovascular treatment of head and neck arteriovenous malformations (AVMs) based on the Yakes AVM classification and correlate treatment approach with clinical and angiographic outcomes.Materials and MethodsA retrospective single-center study was performed in patients who underwent endovascular treatment of head and neck AVMs between January 2005 and December 2017. Clinical and operative records, imaging, and postoperative courses of patients were reviewed. Clinical stage was determined according to the Schobinger classification. AVM architecture and treatment approaches were determined according to the Yakes classification. Primary outcomes were clinical and angiographic treatment success rates and complication rates, with analysis according to the Yakes classification.ResultsA total of 29 patients (15 females) were identified, with a mean age of 30.6 years. Downgrading of the Schobinger clinical classification was achieved in all patients. Lesions included 8 Yakes type IIa, 5 type IIb, 1 type IIIa and IIIb, and 14 type IV. Lesions were treated using an intra-arterial, nidal, or transvenous approach, using ethanol and liquid embolic agents. Arteriovenous shunt eradication of >90% was achieved in 22 of 28 patients (79%), including 9 of 13 (69%) of Yakes type IV lesions and 13 of 15 (87%) of the other types. There were 5 significant complications in 79 procedures (6%), including 4 of 50 (8%) in Yakes type IV lesions.ConclusionsSchobinger stage was downgraded in all patients. Arteriovenous shunt eradication of >90% was achieved in most patients. Yakes type IV lesions required more sessions, and shunt eradication was higher in the Yakes II and III groups.     

Pregnancy Rate and Outcomes following Uterine Artery Embolization for Uterine Arteriovenous Malformations: A Systematic Review and Meta-Analysis

PurposeTo systematically review published studies on the pregnancy rate and outcomes after uterine artery embolization (UAE) for uterine arteriovenous malformations (UAVMs).Materials and MethodsInternational medical databases were searched for all English-language studies published between 2000 and 2022 on patients with UAVMs who had undergone embolization and had a subsequent pregnancy. Data on the pregnancy rate, pregnancy complications, and physiologic status of newborns were extracted from the articles. Ten case series were included in the meta-analysis, and 18 case reports on pregnancy following UAE were reviewed.ResultsIn the case series, 44 pregnancies were reported in 189 patients. The pooled estimate of pregnancy rate was 23.3% (95% confidence interval [CI], 17.3%–29.3%). The pregnancy rate was higher in studies of women with a mean age of ≤30 years (50.6% vs 22.2%; P < .05). The pooled estimate of live birth rate was 88.6% (95% CI, 78.6%–98.7%).ConclusionsAll published series report preservation of fertility and successful pregnancies after embolization of UAVMs. The live birth rate in these series does not differ substantially from that of the general population.     

Venous Sac and Feeding Artery Embolization versus Feeding Artery Embolization Alone for Treating Pulmonary Arteriovenous Malformations: Draining Vein Size Outcomes

PurposeTo investigate and compare venous sac and feeding artery embolization (VFE) with feeding artery embolization (FAE) alone for treatment of pulmonary arteriovenous malformations (PAVMs), based on difference in outcomes in decrease of the size of the draining vein.Materials and MethodsTwenty-six patients (7 male and 19 female; median age [interquartile range], 58 years [46–65 years]) with 42 simple PAVMs treated with coil embolization between August 2005 and December 2018 were retrospectively evaluated. Twenty PAVMs were treated with FAE early in the study period and compared with 22 PAVMs treated with VFE later in the study period. Follow-up computed tomography images obtained 8–20 months after embolotherapy were used for outcome analysis. Data related to patient demographics; follow-up period; baseline diameters of the feeding artery, venous sac, and draining vein; draining vein diameter after treatment; and decrease in the size of the draining vein, including the number reaching a threshold of 70% decrease, were compared between the 2 groups.ResultsThe draining vein decreased in size by a median of 46.4% in the FAE group and 66.3% in the VFE group, and the difference between the 2 groups was statistically significant (P = .009). There were no significant differences in the other parameters.ConclusionsVFE leads to a greater decrease in the size of the draining vein than FAE, suggesting that VFE results in more complete occlusion than FAE for treatment of PAVMs.     

Management of Acquired Uterine Arteriovenous Malformations Associated with Retained Products of Conception

PurposeTo evaluate the efficacy and safety of different treatments for acquired uterine arteriovenous malformations associated with retained products of conception (UAVM-RPOC) and to investigate the role of uterine artery embolization (UAE) in acquired UAVM-RPOC.Materials and MethodsThis was a retrospective study of consecutive patients who were diagnosed with uterine arteriovenous malformation by ultrasound after recently terminated pregnancy. Forty-eight patients were included in this study and were divided into 2 groups (major and minor bleeding groups) according to vaginal bleeding. The treatments were analyzed between groups. Technical and clinical success rates of UAE were analyzed.ResultsOf the 48 patients, 11 patients were in the massive bleeding group and 37 were in the minor bleeding group. Five patients were referred for UAE in each group and UAE was a priority for patients with unstable hemodynamics (chi-square value = 5.524, P =.022). Conservative management, dilation and curettage (D&C), operative hysteroscopy, and UAE were performed in 16 (33%), 18 (38%), 7 (15%), and 13 (27%) patients, respectively. Two patients with ectopic pregnancies suffered uncontrollable bleeding during D&C and required emergent UAE. Three patients underwent UAE before surgery to prevent hemorrhage. The technical and clinical success rates of UAE were 100%. No complications or recurrences occurred.ConclusionsUAE is a safe and effective treatment for UAVM-RPOC and a priority for patients with unstable hemodynamics. Conservative management, D&C, and hysteroscopy are safe and effective for patients with UAVM-RPOC with stable hemodynamics. However, UAVM-RPOC following ectopic pregnancy may have high risks of massive hemorrhage during procedures.     

Retrospective Comparison of Pulmonary Arteriovenous Malformation Embolization with the Polytetrafluoroethylene-Covered Nitinol Microvascular Plug,AMPLATZER Plug,and Coils in Patients with Hereditary Hemorrhagic Telangiectasia

PurposeTo evaluate effectiveness of the polytetrafluoroethylene-covered nitinol mesh microvascular plug (MVP) and compare it with other devices in pulmonary arteriovenous malformation (PAVM) embolization in patients with hereditary hemorrhagic telangiectasia (HHT).Materials and MethodsTwenty-five patients (average age 35 y; range, 15–56 y) with hereditary hemorrhagic telangiectasia (HHT) and de novo PAVM embolization with at least 1 MVP between November 2015 and May 2017 were retrospectively evaluated. Retrospective data were also obtained from prior embolization procedures in the same patient population with other embolic devices dating back to 2008. Technical success, complications, PAVM persistence rates, and category of persistence were analyzed.ResultsIn 25 patients, 157 PAVMs were treated: 92 with MVP, 35 with AMPLATZER vascular plug (AVP), 6 with AVP plus coils, and 24 with coils. The per-PAVM technical success rates were 100% with MVP; 97%, AVP; 100%, AVP plus coils; and 100%, coils. PAVM persistence rates and median follow-up were as follows: MVP, 2% (1/92) (510 d); AVP, 15% (3/20) (1,447 d); AVP plus coils, 20% (1/5) (1,141 d); coils, 46.7% (7/15) (1,141 d). Persistence owing to recanalization for MVP, AVP, AVP plus coils, and coils was 2%, 15%, 0%, and 33%. No difference was found between persistence rates of MVP vs AVP (P = .098). Embolization with a vascular plug (MVP or AVP) with or without coils had a statistically significant lower persistence rate (5.4%) than embolization with coils alone (46.7%) (P = .022).ConclusionsPAVM embolization with MVP had a high technical success rate and a low persistence rate comparable to AVP and lower than coil embolization alone.     

Intraoperative Neuromonitoring during Peripheral Arteriovenous Malformation Embolization

PurposeTo evaluate whether intraoperative neuromonitoring (IONM), including pre-embolization lidocaine injection challenge (“provocative testing”) is associated with reduced risk of irreversible nerve injury during embolization of peripheral arteriovenous malformations (AVMs).Materials and MethodsMedical records of patients with peripheral AVMs who underwent embolotherapy with IONM with provocative testing between 2012 and 2021 were reviewed retrospectively. Data collected included patient demographic characteristics, AVM location and size, embolic agent used, IONM signal changes after lidocaine and embolic agent injections, postprocedural adverse events, and clinical outcomes. Decisions regarding whether embolization would proceed at specific locations were based on IONM findings after the lidocaine challenge and as embolization proceeded.ResultsA cohort of 17 patients (mean age, 27 years ± 19; 5 women) who underwent 59 image-guided embolization procedures with adequate IONM data was identified. No permanent neurologic deficits occurred. Transient neurologic deficits were observed in 3 patients (4 sessions), comprising skin numbness (2 patients), extremity weakness (1 patient), and extremity weakness and numbness (1 patient). All neurologic deficits resolved by postoperative day 4 without additional treatment.ConclusionsIONM, including provocative testing, during AVM embolization may minimize potential nerve injury.     

Comparison of Transthoracic Contrast Echocardiography with High-Resolution Chest CT after Embolization of Pulmonary Arteriovenous Malformation

PurposeTo compare postembolotherapy follow-up graded transthoracic contrast echocardiography (TTCE) and high-resolution computed tomography (CT) of the chest and to evaluate the use of graded TTCE in the early postembolic period.Materials and MethodsThirty-five patients (6 men and 29 women; mean age, 56 years; range, 27–78 years) presenting for postembolotherapy follow-up between 2017 and 2021 with concurrent high-resolution CT and graded TTCE were analyzed retrospectively. Untreated pulmonary arteriovenous malformations (PAVMs) with a feeding artery of ≥2 mm were considered treatable.ResultsNinety-four percent of patients (33 of 35) did not have treatable PAVMs on high-resolution CT. TTCE was negative for shunts (Grade 0) in 34% of patients (n = 12). Of patients with a TTCE positive for shunts (23 of 35, 66%), 83% had a Grade 1 shunt, 13% had a Grade 2 shunt, and 4% had a Grade 3 shunt. No patient with a Grade 0 or 1 shunt had a treatable PAVM on high-resolution CT. Of the 2 patients with PAVMs requiring treatment, one had a Grade 2 shunt and one had a Grade 3 shunt. TTCE grade was significantly associated with the presence of a treatable PAVM on high-resolution CT (P < .01).ConclusionsGraded TTCE predicts the need for repeat embolotherapy and does so reliably in the early postembolotherapy period. This suggests that graded TTCE can be utilized in the postembolotherapy period for surveillance, which has the potential to lead to a decrease in cumulative radiation in this patient population.     

Radiofrequency Ablation of Facial Venolymphatic Malformations: Assessment of Efficacy and Safety and the Role of Injectable Electrodes

PurposeTo evaluate the efficacy and safety of ultrasound (US)-guided radiofrequency (RF) ablation in the treatment of facial microcystic lymphatic malformations (mLMs) or mixed venolymphatic malformations (VLMs) and to introduce the “induced-paralysis” technique with the use of an injectable electrode to minimize neural complications.Materials and MethodsData from patients with symptomatic facial mLMs or mixed VLMs who underwent US-guided RF ablation in 2014–2017 were retrospectively reviewed. Computed tomography (CT) and/or magnetic resonance (MR) imaging was used to localize any functional structures close to the target lesion. Treatment outcome was assessed by 4-point cosmetic grading score (CGS). Treatment outcome was compared between patients with vs without a functional structure close to the lesion and those treated with a noninjectable vs an injectable electrode. Immediate and late complications were assessed during follow-up.ResultsData from 15 patients were evaluated. Initial CGS and median volume were significantly decreased at the last follow-up in all patients (from 4 to 1 and from 7 mL to 0.7 mL, respectively; P < .05). Treatment outcome differed significantly between those with and without a functional structure on CT or MR imaging (P < .05) but showed no difference between noninjectable (n = 9) and injectable electrodes (n = 6). Two cases of transient cranial nerve palsy were seen in the noninjectable electrode group.ConclusionsUS-guided RF ablation is effective in patients with facial mLMs or mixed VLMs. The induced-paralysis technique with an injectable electrode has the potential to ensure technical safety without compromising efficacy.     

Arteriovenous Malformation Associated with Intravenous Leiomyomatosis of the Uterus: Characteristic CT Findings and Treatment by Embolization and Surgery

Seven consecutive female patients with pathologically confirmed arteriovenous malformation (AVM) with intravenous leiomyomatosis (IVL) of the uterus (age range, 32–61 years; mean age, 43 years) treated between 2005 and 2021 from a single institution were reviewed. Computed tomography (CT) findings of congenital pelvic AVM of 10 female patients were compared with those of AVM with IVL. Characteristic CT findings of AVM with IVL revealed a focal soft tissue mass inside a dilated venous structure of the AVM. Multiple sessions of transvenous coil embolization of the AVM with or without the injection of ethanol were performed. After complete (6/7, 86%) or partial (1/7, 14%) embolization of the AVM, complete surgical resection of the IVL and embolized AVM mass was performed in 4 patients. Patients with lung metastasis or residual embolized AVM masses are under follow-up with antiestrogen hormonal therapy.     

Vessel Occlusion using Hydrogel-Coated versus Nonhydrogel Embolization Coils in Peripheral Arterial Applications: A Prospective,Multicenter, Randomized Trial

PurposeTo evaluate the safety and effectiveness of hydrogel-coated coils for vessel occlusion in the body trunk.Materials and MethodsA total of 77 patients with various peripheral vascular lesions, treatable by embolization with coils, were randomized (hydrogel group, n = 38; nonhydrogel group, n = 39). In the hydrogel group, embolization of the target vessel was conducted using 0.018-inch hydrogel-coated coils (AZUR 18; Terumo Medical Corporation, Tokyo, Japan) with or without bare platinum coils. The nonhydrogel group received both bare platinum coils and fibered coils without the use of hydrogel-coated coils.ResultsComplete target vessel occlusion was accomplished in 36 patients in the hydrogel group and 37 patients in the nonhydrogel group. No major adverse events were observed in either group. The median number of coils/vessel diameter and the median total coil length/vessel diameter were significantly larger in the nonhydrogel group than in the hydrogel group (P = .005 and P = .004, respectively). The median embolization length was significantly longer in the nonhydrogel group (31.95 mm) than in the hydrogel group (23.43 mm) (P = .002). If no expansion was assumed, the median packing density in the hydrogel group was 44.9%, which was similar to that in the nonhydrogel group (46.5%) (P = .79). With full expansion assumed, the median packing density in the hydrogel group was 125.7%.ConclusionsHydrogel-coated coils can be safely used for peripheral vascular coil embolization, and hydrogel-coated and conventional coils in combination allow for a shorter embolization segment and shorter coil length.     

Safety and Efficacy of Peripheral Embolization with EASYX Liquid Embolic Agent: A Multicenter Prospective Study

PurposeTo evaluate the clinical safety and efficacy of EASYX, a new nonadhesive precipitating liquid embolic agent based on a polyvinyl alcohol ether polymer labeled with iodine molecules, for peripheral embolization.Materials and MethodsThis open-label prospective multicenter study was conducted on 50 consecutive patients treated with embolization using EASYX in 3 academic hospitals from April 2018 to July 2019. Indications for embolization were symptomatic varicocele (n = 15), type II endoleak (n = 8), acute hemorrhage (n = 16), portal vein embolization (PVE; n = 9), or angiomyolipoma (AML; n = 2). Patient characteristics, technical and clinical success rates, pain at injection, and satisfaction of the interventional radiologists were assessed. Follow-up imaging was performed using ultrasound for varicoceles (at 1 month) and computed tomography (CT) for the other indications (at 3 or 6 months).ResultsThe immediate technical success rate was 98%. The clinical success rates were 100% for acute hemorrhage and type II endoleaks, 89% for PVE, 86% for varicoceles, and 50% for AMLs. Patients who underwent PVE showed significant hypertrophy of the future liver remnant at follow-up (P < .001), and 55.6% of patients proceeded to hepatectomy. The absence of artifacts on imaging allowed improved monitoring of the aneurysmal sac in patients with type II endoleaks. The satisfaction rate of the interventional radiologists was >90% for 5 of 7 items.ConclusionsEASYX as a novel copolymer liquid embolic agent was safe and efficient for peripheral embolization. The absence of tantalum allowed reduced CT artifacts on imaging follow-up, which was especially useful in patients with type II endoleaks.     

Lack of Growth of Small (≤2 mm Feeding Artery) Untreated Pulmonary Arteriovenous Malformations in Patients with Hereditary Hemorrhagic Telangiectasia

PurposeTo assess pulmonary arteriovenous malformation (PAVM) growth among patients with untreated PAVMs using imaging from long-term follow-up per hereditary hemorrhagic telangiectasia international guidelines.Materials and MethodsAnalysis included 88 untreated PAVMs from 21 patients (6 male;15 female; mean age at presentation 47 y; range, 12–68 y). Two CT studies with the longest interval between were evaluated (mean 8.4 y; median 8.8 y; range, 3.1–14.1 y). Measurement of feeding artery diameter and anteroposterior (AP) and mediolateral (ML) sac dimensions for each PAVM was performed separately by 2 radiologists blinded to patient and CT order. Statistical analysis was performed to determine change in size between earliest and follow-up imaging.ResultsMean feeding artery diameter, AP sac dimension, and ML sac dimension were 1.4 mm (range, 0.8–3.7 mm), 4.3 mm (range, 2.1–11.1 mm), and 4.1 mm (range, 1.8–9.2 mm) on earliest imaging and 1.4 mm (range, 0.9–2.6 mm), 4.5 mm (range, 2.2–12.2 mm), and 4.3 mm (range, 2.0–9.6 mm) on follow-up. Model-based mean analysis showed no statistically significant change in dimension of any variable between earliest and follow-up imaging. Secondary analysis including age also found no statistically significant difference (feeding diameter, P = .09; AP sac dimension, P = .9; ML sac dimension, P = .1). Analysis including time between measurements found no significant relationship between change in variables and time (feeding artery diameter, P = .4; AP sac dimension, P = .3; ML sac dimension, P = .06).ConclusionsUntreated PAVMs grew slowly, if at all, in a near-decade span, and any demonstrated growth was minimal. These findings challenge the current recommendation of 3- to 5-year CT follow-up.     

Comparison of Fibered versus Nonfibered Coils for Venous Embolization in an Ovine Model

PurposeTo compare nylon fibered (F) with nonfibered (NF) coils for embolization in an ovine venous model.Materials and MethodsFour- to 8-mm-diameter, 0.035-inch F and NF coils were deployed in 24 veins in 6 sheep. The number of coils, total length of the coils, and length of implanted coil pack required to achieve complete stasis were recorded, as were vessel diameter, radiation dose, ease of packing, damage to embolized vessel, and time to stasis. Venography at 1 and 3 months was used to assess the migration and durability of vessel occlusion. Veins were harvested at 3 months.ResultsF and NF coils were deployed in 24 veins, and stasis was achieved, without immediate coil migration or vessel damage. The mean numbers of F and NF coils per vein were 5 and 8.75, respectively (P = .007). The vessel diameter between the groups was not statistically different. The total coil length (F, 70 cm vs NF, 122.5 cm; P = .0007), coil pack length (F, 29.3 mm vs NF, 39.4 mm; P = .003), time to stasis (F, 5.3 minutes vs NF, 9.0 minutes; P = .008), and radiation dose (F, 25.3 mGy vs NF, 34.9 mGy; P = .037) were significantly different between the groups. Challenges with the animal model prevented conclusive long-term results. Migration occurred with 8 of 11 (72%) coil packs in the femoral veins and 0 of 13 (0%) coil packs in the internal iliac and deep femoral veins. Venography demonstrated that of 16 remaining coil packs, 11 were occluded at 1 month and 10 remained occluded at 3 months.ConclusionsFibers allow for significantly fewer coils to achieve immediate venous occlusion.     

Safety and Efficacy of Retrograde Pyeloperfusion for Ureteral Protection during Renal Tumor Cryoablation

PurposeTo determine safety and efficacy of retrograde pyeloperfusion for ureteral protection during cryoablation of adjacent renal tumors.Materials and MethodsRetrospective review of 155 patients treated with renal cryoablation, including adjunctive retrograde pyeloperfusion, from 2005 to 2019 was performed. Ice contacted the ureter in 67 of the 155 patients who represented the study cohort. Median patient age was 68 years old (interquartile range [61, 74]), 52 patients (78%) were male, and 37 tumors (55%) were clear cell histology. Mean tumor size was 3.4 ± 1.3 cm, and 42 tumors (63%) were located at the lower pole. Treatment-related complication and oncologic outcomes were recorded based on a review of post-procedural images and chart review.ResultsTechnical success of cryoablation was attained in 67 cases (100%), and technical success of pyeloperfusion was attained in 66 cases (99%). A total of 13 patients (19.4%) experienced SIR major C or D complications related to the procedure, including hemorrhage (n = 4), urine leak (n = 3), transient urinary obstruction (n = 2), pulmonary embolism (n = 1), hypertensive urgency (n = 1), acute respiratory failure (n = 1), and ureteropelvic junction (UPJ) stricture (n = 1). No complications were attributable to pyeloperfusion. Three of 45 patients with biopsy-proven renal cell carcinoma experienced local recurrence resulting in local recurrence-free survival of 92% (95% confidence interval, 81.5%–100%) 3 years after ablation.ConclusionsRetrograde pyeloperfusion of the renal collecting system is a relatively safe and efficacious option for ureteral protection during renal tumor cryoablation. This adjunctive procedure should be considered for patients in whom cryoablation of a renal mass could potentially involve the ureter.