Embolization using hydrogel-coated coils for pulmonary arteriovenous malformations

A Meta-Analysis and Meta-Regression of Embolisation Outcomes of Pulmonary Arteriovenous Malformations

PURPOSE

Embolisation is a widely utilised therapeutic intervention for pulmonary arteriovenous malformation (PAVM). We conducted a meta-analysis to evaluate outcomes of PAVM embolisation and factors associated with embolisation outcomes.

METHODS

MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials (CENTRAL) were searched from 2000 to July 2022 on studies that assessed embolisation outcomes of PAVM. Immediate technical success rate defined as the complete occlusion of the PAVM at the time of embolisation and treatment success rate defined as ≥ 70% venous sac reduction on follow-up imaging were pooled from included studies with use of random effects proportion meta-analysis. Heterogeneity across studies was assessed with the I2 statistic.

RESULTS

Forty-four studies including 1865 patients (604 (32%) males, mean age (range) 45 (24-59) years, 1125 (60%) had hereditary haemorrhagic telangiectasia (HHT)) were included in the meta-analysis. Studies included a total of 4314 PAVMs of which 4047 (94%) were treated. Studies reported morphology of 3074 PAVMs (2519 (58%) simple and 555 (13%) complex). The pooled overall immediate technical success rate for PAVM embolisation was 99%, 95% CI (98-100%) and the treatment success rate was 86%, 95% CI (84-89%). Younger age (p = 0.041), simple PAVM (0.020), and embolisation using plugs (p = 0.001) were associated with higher treatment success. Feeding artery and sac embolisation (p = 0.021) and using coils (p = 0.001) were associated with lower treatment success. There was no significant difference in recanalisation rate between different embolisation agents (OR 0.64, 95% CI -0.09- 1.38).

CONCLUSION

This meta-analysis shows that PAVM embolisation is safe and effective. Higher treatment success rates for PAVM embolisation can be achieved using plugs as the primary embolisation agent. Embolisation agent used had no effect on recanalisation rates.

High-density pulmonary lesions: Review in chest imaging

High-density pulmonary lesions are frequently seen in chest imaging, and it is important to identify their different causes. Radiologists must be able to distinguish between common and rare conditions in order to provide the best diagnosis and treatment. This article provides an overview of the various causes and imaging features of high-density lesions in the lungs. The lesions are classified into various categories, such as pulmonary nodules, inflammatory conditions, deposition diseases, contrast-related lesions, and thoracic devices. A clear understanding of these categories can help radiologists accurately diagnose and manage high-density pulmonary lesions encountered in practice.

Selective Angiographic Evaluation in Patients with Simple-Type Pulmonary Arteriovenous Malformations Treated with Vascular Plug

PURPOSE

To evaluate the angiographic recanalization rate of patients who underwent embolization juxta-proximal to the sac with AMPLATZER Vascular Plug type IV (AVP IV) for a simple pulmonary arteriovenous malformation (PAVM).

MATERIAL AND METHODS

Ten patients (7 females and 3 males; median age, 47 years [range 28-83 years]) with 19 simple-type PAVMs who underwent embolization using an AVP IV between May 2015 and November 2021 were included in this retrospective study. The median feeding artery diameter on computed tomography was 4.0 mm (range 3-5.9 mm), and the median ratio of AVP IV size to feeding artery diameter on computed tomography was 1.5 (range 1.3-2.1). Technical success was defined by AVP IV placement at the junction between the pulmonary artery and the sac, or the pulmonary artery within 1 cm from the junction and beyond the last normal branch. The primary endpoint was the PAVM recanalization rate in selective or segmental pulmonary angiography performed 1 year post-embolization.

RESULTS

The technical success rate of embolization juxta-proximal to the sac for simple-type PAVMs was 100%. None of the 19 lesions showed recanalization in pulmonary angiography performed 1 year after embolization. One patient experienced hemoptysis and pneumonia.

CONCLUSION

Embolization of simple-type PAVMs' feeding vessel using AVP IV is safe and effective, with a high technical success rate and no recanalization on pulmonary angiography performed at 1 year post-embolization.

LEVEL OF EVIDENCE: 4

Effectiveness of Embolization for Pulmonary Arteriovenous Malformations from Distal of the Last Normal Branch of the Pulmonary Artery

Purpose

This retrospective study of patients with pulmonary arteriovenous malformations aims to assess the efficacy of embolization distal to the origin of the last normal branch of the pulmonary artery.

Material and Methods

A total of 30 consecutive patients with 38 untreated pulmonary arteriovenous malformations underwent coil embolization distal to the origin of the last normal branch of the pulmonary artery between September 2015 and October 2021. The median (interquartile range) age of patients (5 males, 25 females) was 59 years (50-68 years old), and the median (interquartile range) sizes of the feeding artery and sac were 2.9 mm (2.3-3.8 mm) and 6.7 mm (5.4-9.7 mm), respectively. The technical success rate, persistence rate, and treatment-related complications were evaluated. Technical success was defined as the inability to identify the draining vein on feeding arteriography after coil embolization. Persistence was assessed using time-resolved magnetic resonance angiography.

Results

Coil embolization was successful in all patients (100%). There was no persistence during a median (interquartile range) follow-up period of 23 months (10-45 months) for the 38 pulmonary arteriovenous malformations embolized with coils. No major complications were reported. Only minor complications following embolization occurred in 4 of 36 sessions, including local pain in 2 sessions (6%) and hemosputum in 2 sessions (6%).

Conclusions

Embolization distal to the origin of the last normal branch of the pulmonary artery is effective in preventing the persistence of pulmonary arteriovenous malformations.

Efficacy and Safety of Venous Sac Embolization With or Without Feeding Artery Embolization Versus Feeding Artery Embolization Alone in the Management of Pulmonary Arteriovenous Malformations: A Systematic Review and Meta-analysis

PURPOSE

To evaluate by meta-analysis the safety and efficacy of venous sac embolization (VSE) with or without feeding artery embolization versus feeding artery embolization (FAE) alone in the management of pulmonary arteriovenous malformations (PAVMs).

METHODS

This systematic review and meta-analysis was performed and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A systematic literature search was performed in MEDLINE, Embase, and Scopus till August 31, 2021 to identify studies comparing the safety and efficacy of VSE with or without FAE versus FAE alone in PAVMs. The success of treatment was assessed by comparing the number of PAVMs with ≥70% decrease in the size of draining vein/sac between the 2 groups. The pooled odds ratio (OR) and 95% confidence interval (95% CI) were calculated using the random-effects inverse-variance model and were used to compare pooled therapeutic efficacy between the groups.

RESULTS

Three studies were found eligible for the meta-analysis. The included studies had a total of 169 patients (119 females and 50 males). The total number of PAVMs was 298, and hereditary hemorrhagic telangiectasia was present in 119 patients. The success of treatment was higher with VSE as compared to FAE (OR=3.54, 95% CI=1.66-7.56). The minor complications were similar in both groups, and one major complication occurred in the FAE group. More coils were used in the VSE group.

CONCLUSIONS

The present systematic review and meta-analysis has consolidated the evidence that VSE with or without FAE is more efficacious than FAE alone in the management of PAVMs without any increase in the associated risk of sac rupture or coil migration.

CLINICAL IMPACT

Until high-quality data from a prospective, multicentric, randomized controlled trial becomes available, the evidence consolidated by the present systematic review and meta-analysis showing the efficacy of venous sac embolization (with or without feeding artery embolization) over feeding artery embolization alone, can be used for clinical decision-making in the management of pulmonary arterio-venous malformations.

OnyxTMGel or Coil versus Hydrogel as Embolic Agents in Endovascular Applications: Review of the Literature and Case Series

This review focuses on the use of conventional gel or coil and "new" generation hydrogel used as an embolic agent in endovascular applications. In general, embolic agents have deep or multidistrict vascular penetration properties as they ensure complete occlusion of vessels by exploiting the patient's coagulation system, which recognises them as substances foreign to the body, thus triggering the coagulation cascade. This is why they are widely used in the treatment of endovascular corrections (EV repair), arteriovenous malformations (AVM), endoleaks (E), visceral aneurysms or pseudo-aneurysms, and embolisation of pre-surgical or post-surgical (iatrogenic) lesions. Conventional gels such as Onyx or coils are now commercially available, both of which are frequently used in endovascular interventional procedures, as they are minimally invasive and have numerous advantages over conventional open repair (OR) surgery. Recently, these agents have been modified and optimised to develop new embolic substances in the form of hydrogels based on alginate, chitosan, fibroin and other polymers to ensure embolisation through phase transition phenomena. The main aim of this work was to expand on the data already known in the literature concerning the application of these devices in the endovascular field, focusing on the advantages, disadvantages and safety profiles of conventional and innovative embolic agents and also through some clinical cases reported. The clinical case series concerns the correction and exclusion of endoleak type I or type II appeared after an endovascular procedure of exclusion of aneurysmal abdominal aortic (EVAR) with a coil (coil penumbra released by a LANTERN microcatheter), the exclusion of renal arterial malformation (MAV) with a coil (penumbra coil released by a LANTERN microcatheter) and the correction of endoleak through the application of Onyx 18 in the arteries where sealing by the endoprosthesis was not guaranteed.

Transarterial Embolization of Simple Pulmonary Arteriovenous Malformations: Long-Term Outcomes of 0.018-Inch Coils versus Vascular Plugs

PURPOSE

To compare the safety, effectiveness, and persistence rates of 0.018-inch coils with those of Amplatzer vascular plugs (AVPs; Abbott Vascular, Abbott Park, Illinois) for the treatment of pulmonary arteriovenous malformations (PAVMs) in response to a growing concern that 0.018-inch coil embolization would increase the long-term persistence rate.

MATERIALS AND METHODS

This is a retrospective, single-center study of a database (2002-2020) of 633 PAVM embolizations. Complex PAVMs and those not embolized with 0.018-inch coils or plugs were excluded. PAVM embolization material was classified into 4 groups: (a) 0.018-inch nonfibered coils (NFCs), (b) 0.018-inch fibered coils (FCs), (c) NFCs and FCs, or (d) plugs. Persistence was defined as flow through the PAVM on digital subtraction angiography (DSA) or as <30% diameter reduction of the aneurysmal sac on unenhanced computed tomography (CT). Kaplan-Meier analysis and Cox regression were used to assess PAVM's persistence-free survival.

RESULTS

A total of 312 PAVM embolizations with NFCs (43 PAVMs), FCs (127 PAVMs), NFCs and FCs (12 PAVMs), or plugs (130 PAVMs) in 109 patients (28% men; mean age = 49 years) were included. All PAVM embolizations were technically successful without any major adverse events. PAVM persistence-free survival rates at 10 years' follow-up were 40.8% versus 44.7% in the NFC and FC groups (P = .22) and 47.3% versus 81.0% in the 0.018-inch coil (NFC or FC) and plug groups (P < .0001), respectively. There were 0.43 (79/182) and 0.08 (10/130) re-embolization procedures per PAVM in the 0.018-inch coil and plug groups, respectively (P < .001).

CONCLUSIONS

PAVM embolization with 0.018-inch coils was safe, but persistence rate with PAVM embolization was significantly higher than that with plugs, with no significant differences between FCs and NFCs.

Pregnancy and delivery after percutaneous embolization with a combination of microvascular plugs and hydrogel-coated coils for unilateral diffuse pulmonary arteriovenous malformations: a case report

Background

Pulmonary arteriovenous malformations (PAVMs) are abnormal communications between the pulmonary arteries and veins; right-to-left shunts can cause hypoxaemia, emboli to systemic circulation, and brain abscesses. Cyanosis during pregnancy may increase the probability of premature birth or spontaneous abortion and may increase maternal cardiac complications.

Case summary

We describe a case of a 24-year-old woman with diffuse multiple PAVMs localized to the left inferior lobe and chronic cyanosis. She had increased exertional fatigue and chronic headaches and was New York Heart Association class II, although her rest sitting peripheral oxygen saturation (SpO2) had remained unchanged at 83% over the past 20 years. She underwent percutaneous embolization with microvascular plugs and hydrogel-coated coils. A microvascular plug was placed as an anchor near the venous sac, followed by hydrogel-coated coil embolization of the proximal pulmonary artery. A total of six sessions of catheter intervention were performed. The embolization was successful, her hypoxaemia was relieved, and she was able to conceive and deliver. Three years have passed since the last session, and SpO2 97% has been maintained.

Discussion

In the treatment of complex PAVMs, the combination of microvascular plugs and hydrogel-coated coils resulted in shorter procedure time, lower risk of migration of the embolus to the pulmonary veins, and less recanalization and revascularization. Percutaneous embolization of PAVMs resulted in safe delivery for the mother and child.

Diagnosis and Management of Persistent Pulmonary Arterio-venous Malformations following Embolotherapy

Embolotherapy is the primary treatment for pulmonary arterio-venous malformations (PAVMs). Approximately, 2-25% of PAVMs demonstrate persistence following embolization. Early identification and treatment of persistent PAVMs are critical to mitigating life threatening complications. The presence of prior embolic devices and complex angioarchitecture of persistent PAVMs pose technical challenges during repeat embolotherapy. In this article, we review patterns of persistence, factors affecting the persistence, endovascular treatment techniques, and outcomes.

Vascular occlusion with 0.035-inch hydrogel expandable coils in congenital heart diseases and vascular anomalies

BACKGROUND

We present our experience with transcatheter vascular occlusion using 0.035-inch hydrogel expandable coils, which has been reported only in a few cases in the pediatric cardiology fields.

METHODS

This study is a retrospective analysis of all patients who underwent transcatheter embolization with 0.035-inch hydrogel coils at the Department of Pediatrics, Okayama University Hospital, between October 2018 and September 2020.

RESULTS

Twenty patients with a median age of 5.1 years (0.05-26.0 years) and a median weight of 13.8 kg (3.0-56.8 kg) were included. A total of fifty-four 0.035-inch hydrogel coils, including 35 Azur 35 and nineteen Azur CX 35 coils (Terumo, Tokyo, Japan), were successfully deployed in 22 target vessels. The target vessels consisted of 10 aortopulmonary collaterals, 8 veno-venous collaterals, and 4 pulmonary arteriovenous malformations. We achieved technical success in all the target vessels. In total, the mean target vessel diameter was 4.4 mm, the mean number of 0.035-inch hydrogel coils was 2.5 per vessel. The mean device to vessel ratio was 1.6 for the anchor coil and 1.2 for the additional coil. Post-implantation angiograms revealed that the primary occlusion rate was 18/22 (82%). There were no periprocedural complications.

CONCLUSIONS

The 0.035-inch hydrogel expandable coils are effective and safe in patients with congenital heart disease and vascular anomalies. These occlusion devices could be valuable options for interventional pediatric cardiologists.

Reduced nontarget embolization and increased targeted delivery with a reflux-control microcatheter in a swine model

PURPOSE

To evaluate the potential differences in non-target embolization and vessel microsphere filling of a reflux-control microcatheter (RCM) compared to a standard end-hole microcatheter (SEHM) in a swine model.

MATERIALS AND METHODS

Radiopaque microspheres were injected with both RCM and SEHM (2.4-Fr and 2.7-Fr) in the kidneys of a preclinical swine model. Transarterial renal embolization procedures with RCM or SEHM were performed in both kidneys of 14 pigs. Renal arteries were selectively embolized with an automated injection protocol of radio-opaque microspheres. Ex-vivo X-ray microtomography images of the kidneys were utilized to evaluate the embolization by quantification of the deposition of injected microspheres in the target vs. the non-target area of injection. X-ray microtomography images were blindly analyzed by five interventional radiologists. The degree of vessel filling and the non-target embolization were quantified using a scale from 1 to 5 for each parameter. An analysis of variance was used to compare the paired scores.

RESULTS

Total volumes of radio-opaque microspheres injected were similar for RCM (11.5±3.6 [SD] mL; range: 6-17mL) and SEHM (10.6±5.2 [SD] mL; range: 4-19mL) (P=0.38). The voxels enhanced ratio in the target (T) vs. non-target (NT) areas was greater with RCM (T=98.3% vs. NT=1.7%) than with SEHM (T=89% vs. NT=11%) but the difference was not significant (P=0.30). The total score blindly given by the five interventional radiologists was significantly different between RCM (12.3±2.1 [SD]; range: 6-15) and the standard catheter (11.3±2.5 [SD]; range: 4-15) (P=0.0073), with a significant decrease of non-target embolization for RCM (3.8±1.3 [SD]; range: 3.5-4.2) compared to SEHM (3.2±1.5 [SD]; range: 2.9-3.5) (P=0.014).

CONCLUSION

In an animal model, RCM microcatheters reduce the risk of non-target embolization from 11% to 1.7%, increasing the delivery of microspheres of 98% to the target vessels, compared to SEHM microcatheters.