Dual-lumen balloon catheters may improve liquid embolization of vascular malformations: an experimental study in Swine

Experimental investigation of transvenous embolization of arteriovenous malformations using different in vivo models

BACKGROUND

Transvenous embolization (TVE) is an emerging technique for the endovascular treatment of cerebral arteriovenous malformations (AVMs). The aim of this study was to investigate two in vivo AVM models and to assess TVE techniques using these models.

METHODS

Blood flow in the porcine rete mirabile (RM) was modified by either creating a carotid-jugular fistula or by placing a balloon guide catheter in the carotid artery. The RM was embolized with precipitating hydrophobic injectable liquid (PHIL) 25% via transarterial embolization (TAE; control group) and compared with TVE applying the transvenous retrograde pressure cooker technique and TVE using a Woven EndoBridge (WEB) device for flow control (n=6, respectively). The embolization extent (penetration of the RM), the number of events of reflux or embolization distal to the RM and the procedure times were assessed.

RESULTS

The modified RM could be successfully used for embolization in all cases. There were no significant differences regarding the outcome parameters between the two AVM models (fistula or balloon). TVE using the pressure cooker technique led to a higher extent of embolization (median 98.8% vs 63.5%; p=0.008), a lower number of reflux or distal embolization events (p<0.001) and a shorter procedure time (p<0.001) compared with conventional TAE. TVE using a WEB device for flow control was technically feasible and achieved a moderate extent of embolization (median 83.8%).

CONCLUSION

After surgical or endovascular modification, the porcine RM is a feasible in vivo AVM model for the investigation of TVE techniques. TVE using the pressure cooker technique is superior to conventional TAE in this experimental model.

Endovascular balloon-assisted liquid embolisation of soft tissue vascular malformations: technical feasibility and safety

Purpose

Arteriovenous malformations (AVMs) are abnormal communications between arteries and veins without an intervening capillary system. The best endovascular treatment option for these is unclear and may involve multiple staged procedures using a variety of embolic materials. We report our initial experience using a modified version of a previously published neurointerventional technique to treat soft tissue AVMs with single-stage curative intent.

Materials and methods

Soft tissue AVMs treated endovascularly using either sole arterial or combined arterial and venous balloon-assisted techniques with liquid embolic agents were retrospectively identified over a 3.5 year period (January 2017 to June 2020)) at two centres. Clinical, pre-operative radiological, procedural technical and post treatment details were recorded.

Results

Seven patients were treated for symptomatic soft tissue arteriovenous malformations. These AVMs were located in the peripheral limbs (five), tongue (one) and uterus (one). Curative treatment was achieved in 6/7 patients with one patient requiring a second treatment approximately 1 year later. A variety of liquid embolisation agents (LEAs) including sclerosants and polymers were used. Clinical success rate was 100% following treatment. One patient experienced expected temporary post-operative tongue swelling requiring tracheostomy occurred following embolisation of the lingual AVM. A minor complication in a second patient was due to an access site haematoma developed following treatment of the hand AVM requiring surgical intervention. No long-term sequelae or additional complications were observed.

Conclusion

Endovascular arterial and venous balloon assisted LEA embolization of soft tissue AVMs with curative intent is feasible. This technique may provide an alternative treatment option for achieving durable occlusion for complex soft tissue AVMs.

Comparing N-hexyl cyanoacrylate (Magic Glue) and N-butyl cyanoacrylate (NBCA) for neurovascular embolization using the pressure cooker technique: An experimental study in swine

BACKGROUND

The pressure cooker (PC) technique uses a second microcatheter to produce a proximal occlusion to prevent the reflux of liquid embolic agent (LEA) injected through a more distal microcatheter, and can be used to treat arteriovenous malformations and dural arteriovenous fistulae. The liquid embolic Magic Glue (MG) (N-hexyl cyanoacrylate (NHCA)) has been introduced as an alternative to N-butyl cyanoacrylate (NBCA). Our goals were to compare the extent of embolization of rete mirabile with or without the PC technique using NBCA or MG, and to compare the proximal occlusions obtained with MG or NBCA while using the PC technique in a renal arterial model.

METHODS

Rete mirabile were embolized with (n = 4) and without (n = 4) the PC technique, using MG (n = 4) or NBCA (n = 4). A renal arterial model was then used to study the characteristics of the MG plug (n = 10) used for the PC technique, and resistance to catheter withdrawal as compared to NBCA (n = 4). Specimens were analyzed macro- and microscopically and compared to angiographic results.

RESULTS

Extent of rete embolization with CYA agents was not significantly greater when using the PC technique. Results were similar with both types of cyanoacrylate (p = 0.657). The force necessary to withdraw the microcatheter was less with MG than with NBCA (p = 0.035).

CONCLUSION

MG was similar to NBCA in extent of rete embolization. Less traction force was necessary to withdraw trapped non-detachable microcatheters using MG compared to NBCA.

Pial arteriovenous fistula: A clinical and neuro-interventional experience of outcomes in a rare entity

Purpose:

Pial arteriovenous fistulae (PAVF) are rare intracranial vascular malformations, predominantly seen in children and distinct from arteriovenous malformations and dural arteriovenous fistulae. PAVF often leads to high morbidity and mortality. The aim of our study was to describe the clinical features and endovascular management of PAVF at various intracranial locations; to analyze the use of liquid embolic agents and coils alone or in combination in the treatment of PAVF and to analyze the outcome of embolization.

Materials and Methods:

Retrospective review of diagnostic angiography and neurointerventional database of our institution identified a cohort of 15 patients with non-galenic PAVF from 2008 to 2014 out of 6750 patients. Fourteen patients were treated endovascularly with coils and liquid embolic materials in combination or alone. Patients were followed up for evaluation of prognosis.

Results:

Age of the patients ranged from 3 to 37 years. Most patients were male and most common presentation was headache followed by seizure. Most common location of fistula was frontal lobe. The most common type was single artery single hole fistula with venous varix. Satisfactory obliteration was seen in all cases. One patient developed intraparenchymal hematoma on the first post procedural day and outcome was poor.

Conclusions:

PAVF are rare intracranial vascular malformations which can effectively be managed endovascularly with liquid embolic, coils alone, or in combination. Complete occlusion of the fistula can be achieved in most cases in a single sitting with a reasonable morbidity related to the procedure, compared with the natural history of this disease.

Inline Balloon Occlusion-Assisted Delivery of Ethylene Vinyl Alcohol Copolymer for Peripheral Arterial Applications: A Multicenter Case Series

PURPOSE

To assess the feasibility, safety, and efficacy of balloon-assisted delivery of ethylene vinyl alcohol copolymer (EVOH) for a range of peripheral arterial applications.

MATERIALS AND METHODS

Six academic medical centers entered retrospective data on 46 consecutive patients (27 men, 19 women; ages, 11-94 y; mean age, 50.3 y) who underwent 60 balloon-assisted EVOH procedures. The cohort was restricted to procedures involving peripheral, nonneural arteries 1-5.5 mm in diameter. Clinical indications included a wide range of vascular pathologic conditions (most commonly arteriovenous malformations [n = 20], renal angiomyolipomas [n = 8], and acute hemorrhage [n = 9]) and targeted visceral and musculoskeletal peripheral arteries. Data collected included sex, age, clinical indication, arterial pathology, arteries embolized, type of occlusion balloon microcatheter, type and concentration of EVOH agent, effectiveness as an embolic backstop, vessels protected, adequacy of EVOH cast penetration, catheter extraction, nontarget embolization, and complications.

RESULTS

Balloon occlusion prevented EVOH reflux in 59 of 60 procedures (98.3%). Nontarget EVOH embolization occurred in 2 procedures (3.3%). Adequate EVOH cast penetration and complete filling of the target pathologic structure were seen in 57 of 60 procedures (95%). Balloon deflation and uneventful extraction occurred in all procedures; small EVOH fragments detached into target arteries in 2 cases. One major (1.7%) and 2 minor (3.3%) complications occurred.

CONCLUSIONS

Balloon-assisted EVOH embolization of peripheral arteries is feasible, safe, effective, and versatile. The primary advantage of balloon-assisted EVOH embolization is the ability to apply more injection pressure to advance the EVOH cast assertively into the pathologic structure(s).

Investigation of a New Version of the Liquid Embolic Agent PHIL with Extra-Low-Viscosity in an Endovascular Embolization Model

BACKGROUND AND PURPOSE

The type and composition of an embolic agent have a relevant influence on the performance of endovascular embolization. The aim of this study was to investigate a new version of the liquid embolic agent precipitating hydrophobic injectable liquid (PHIL) with extra-low-viscosity in an in vivo embolization model.

MATERIALS AND METHODS

Twenty-four embolization procedures were performed in the porcine rete mirabile. Eight embolizations were performed with PHIL 25% low viscosity, Squid 12, and standard PHIL 25%, respectively. Procedure time, required volume of embolic agent, visibility of the embolic agent, embolization control, embolization extent (ie, penetration of the rete mirabile), amount of reflux, and degree of embolization distal to the rete mirabile were assessed.

RESULTS

All embolic agents were adequately visible. The embolization extent was not significantly different among the 3 investigated agents; however, there was a tendency toward a higher embolization extent for PHIL 25% low viscosity (median embolization extent: 88% [PHIL 25% low viscosity]; 65% [Squid 12]; 60% [PHIL 25%]; P = .146). The amount of reflux was significantly lower for the extra-low-viscosity agents PHIL 25% low viscosity and Squid 12 compared with the standard PHIL 25% (median reflux distance: 8 mm [PHIL 25% low viscosity]; 6 mm [Squid 12]; 17 mm [PHIL 25%]; P = .011). All other embolization features did not differ among agents.

CONCLUSIONS

PHIL 25% low viscosity is a promising liquid embolic agent for endovascular embolization, featuring effective distal penetration, adequate visibility, a low amount of reflux, and good flow control.

Safety and Feasibility of Balloon-Assisted Embolization with Onyx of Brain Arteriovenous Malformations Revisited: Personal Experience with the Scepter XC Balloon Microcatheter

Background/Objective

Compliant dual-lumen balloon microcatheters have been used to perform balloon-assisted embolization (BAE) of brain arteriovenous malformations (AVMs) with ethylene vinyl alcohol copolymer (Onyx). However, vessel rupture and microcatheter retention have been reported from BAE using these microcatheters. Using an extra-compliant balloon microcatheter (Scepter XC; Microvention, Tustin, CA, USA) could help avoid pial vessel rupture during BAE. We herein report our experience using this balloon microcatheter for BAE.

Methods

This retrospective study included patients who underwent BAE of brain AVMs at our institution between June 2012 and March 2017.

Results

The extra-compliant Scepter XC balloon microcatheter was used for BAE of brain AVMs in 23 patients aged 44.3 ± 16.7 years (range 0-65 years). A total of 40 intracranial vessels (39 pial arteries and 1 pial vein) were catheterized and embolized during 30 separate sessions. In all instances, the balloon microcatheter could be successfully advanced to the AVM nidus. A mean volume of 2.4 ± 1.7 mL (range 0.65-4.6 mL) of Onyx was injected per session. There were no instances of vessel rupture, microcatheter retention, or stroke.

Conclusion

Utilization of the extra-compliant balloon microcatheter results in safe and effective BAE, which adds to the growing experience with BAE for AVM treatment.

In vivo evaluation of the new PHIL low viscosity in a swine rete mirabile model

INTRODUCTION

Few liquid embolic materials are available for treatment of arteriovenous malformations. We describe the in vivo experience with the new PHIL low viscosity (LV) liquid embolic agent in a swine rete mirabile model.

METHODS

Eight swine were treated. Two animals underwent embolization of a rete with PHIL LV and the contralateral rete with Squid 12 (euthanized the same day). Six animals underwent embolization of the right rete: two with balloon flow arrest (euthanized at 14 d) and four with a microcatheter alone (euthanized at 14 and 90 d). Performance characteristics of the embolic agents were evaluated. Microscopic and histological analysis of the harvested retia was performed. Macroscopic examinations and high contrast digital-based radiographs of the central nervous system were obtained.

RESULTS

We did not experience any technical complication during embolization of each rete. Overall occlusion ability, on/off injection and ease to retrieve the microcatheter/balloon with PHIL LV were optimal. Fluoroscopic visualization of the PHIL LV cast was adequate to optimal. Average embolization time with flow arrest was 9.5 min versus 19.5 min with microcatheter plugging. Embolizations with PHIL LV required less volume and were shorter when compared to Squid 12. Subacute (14 d) and chronic (90 d) microscopic and histological analysis demonstrated minimal inflammatory changes in the perivascular tissues and permanent occlusion of the embolized vasculature.

CONCLUSION

In this swine rete model, the new PHIL LV embolic agent had an excellent embolization performance. Vessels embolized remained occluded up to 90 d from the procedure with minimal inflammatory changes.

Extra-small dual-lumen micro-balloon catheters can improve endovascular embolization: an experimental in vivo and in vitro study

BACKGROUND

The embolization technique can have significant impact on the success of endovascular embolization.

OBJECTIVE

To evaluate the feasibility, embolization characteristics, and embolization extent with a newly developed extra-small micro-balloon catheter in an in vivo and in an in vitro embolization model in comparison with standard microcatheter embolizations.

MATERIALS AND METHODS

Twenty-eight embolization procedures were performed in the porcine rete mirabile (RM) and in an in vitro embolization model, using either an extra-small (distal outer diameter 1.6 F) dual-lumen micro-balloon catheter or a standard microcatheter. Precipitating hydrophobic injectable liquid (PHIL) was used as embolic agent. Procedure times, number of injections, required volume of embolic agent, and embolization extent (percentage of embolized RM in postinterventional X-ray scans or number of filled sections of the in vitro model) were assessed. Histopathological analyses were performed.

RESULTS

Total procedure time was significantly shorter (in vivo: 123 s vs 615 s (medians), P=0.001; in vitro: 180 s vs 496 s (medians), P=0.001), number of reflux events was significantly lower (in vivo: 0 vs 9 (medians), P=0.001; in vitro: 0 vs 3 (medians), P=0.001), and embolization extent was significantly higher (in vivo: 96.9% vs 65.6% (medians), P=0.011; in vitro: 26 vs 18 filled sections (medians); P=0.041) for the micro-balloon catheter groups. There was antegrade movement of the PHIL cast after balloon deflation in one in vitro embolization procedure and spontaneous balloon deflation with subsequent reflux in one in vivo embolization procedure.

CONCLUSION

Extra-small dual-lumen micro-balloon catheters can improve endovascular embolization in comparison with standard microcatheter embolization.

Assessment of human placenta as an ex-vivo vascular model for testing of liquid embolic agent injections with adjunctive techniques

PURPOSE

This project sought to test the utility of post-delivery human placenta (HP) as a vascular model for liquid embolic agent (LEA) simulation, along with adjunctive techniques.

MATERIALS AND METHODS

Twelve LEA injections were performed under fluoroscopy in HP with two reflux control methods: dual lumen 'mini' balloon-catheter (n=9); and injection after proximal nBCA plug formation through a second microcatheter ('pressure cooker') (n=3). Measured outcomes included liquid embolic agent (LEA) advancement and reflux. Reflux was categorized into three grades: grade 0=no reflux; grade 1=occlusion of side branches without reflux beyond the balloon or plug; and grade 2=reflux beyond the balloon or plug.

RESULTS

Simulation success was greater when a balloon was used rather than with a nBCA plug (89% vs 33%, P=0.054). In eight successful balloon-assisted injections, the reflux grades were: 50% grade 0; 12.5% grade 1; and 37.5% grade 2. The one successful nBCA plug injection had grade 2 reflux. All grade 2 balloon injections occurred when the balloon was positioned across a vessel bifurcation.

CONCLUSIONS

HP provides excellent simulation for liquid embolic agents with a dual lumen balloon catheter.

Evaluation of a novel liquid embolic agent (precipitating hydrophobic injectable liquid (PHIL)) in an animal endovascular embolization model

BACKGROUND

The choice of the embolic agent and the embolization technique can have a significant impact on the success of endovascular embolization.

OBJECTIVE

To evaluate a novel iodinated copolymer-based liquid embolic agent (precipitating hydrophobic injectable liquid (PHIL)) in the porcine rete mirabile (RM), serving as an endovascular embolization model. Onyx, as an established liquid embolic agent, served as comparator.

MATERIALS AND METHODS

Sixteen embolization procedures were performed using PHIL (n=8) or Onyx (n=8) as liquid embolic agent. Waiting time between injections was set to 30 or 60 s (n=4 per study group). Survival time after intervention was 2 hours or 7 days. Embolization characteristics (eg, procedure times, number of injections and volume of embolic agent) and embolization extent (percentage of embolized RM in post-interventional x-ray) were assessed. Post-interventional CT and histopathological analyses were performed.

RESULTS

Embolization characteristics and embolization extent were not significantly different for PHIL and Onyx, including subgroups (eg, embolization extent 44% vs 69% (medians); p=0.101). For PHIL, extension of the waiting time from 30 to 60 s led to a significantly higher embolization extent (24% vs 72% (medians); p=0.035). Moderate disintegration and mild inflammation of the embolized blood vessels were present for both embolic agents.

CONCLUSION

PHIL is feasible for transarterial embolization in an acute and subacute endovascular embolization model. In this preliminary experimental in vivo study, embolization characteristics, embolization extent, and biocompatibility seem to be similar to those of Onyx.

Preliminary experience with precipitating hydrophobic injectable liquid in brain arteriovenous malformations

Advancement in microcatheter design and emergence of new embolic agents offer better results in endovascular treatment of brain arteriovenous malformations (AVMs). Precipitating hydrophobic injectable liquid (PHIL) (Microvention) is a newly introduced dimethyl sulfoxide-based embolic agent for endovascular use. Herein, we present three patients who underwent endovascular treatment of brain AVMs with PHIL, followed by surgical resection. Endovascular features and same-day surgical handling of the new embolic agent PHIL are presented along with histopathologic changes in the acute stage in brain AVMs are presented, and its major differences from Onyx. In our series, PHIL had moderate inflammatory reaction in the acute stage without any associated angionecrosis that is different than Onyx which cause mild inflammatory reaction with angionecrosis. Smallest vessel containing PHIL was 2.9 μm compared to 5 μm with Onyx, which suggests better penetration.

Double-lumen balloon for Onyx® embolization via extracranial arteries in transverse sigmoid dural arteriovenous fistulas: initial experience

Transverse-sigmoid dural arteriovenous fistulas (TS DAVFs) can be challenging to treat by endovascular means. Indeed, a total cure of the fistula can only be achieved when complete occlusion of the fistulous point(s) is obtained by penetration of the embolic agent. However, in some cases, especially for transosseous branches from extracranial arteries like the occipital artery (OcA) or the superficial temporal artery (STA), such penetration is usually poor, leading to major proximal reflux and incomplete fistula obliteration. We present three cases of embolization in two patients with TS DAVF through the OcA and/or the STA with Onyx® using a double-lumen balloon (Microvention, Tustin, CA, USA). This technique allows the penetration of the embolic agent in the transosseous branches by forming a counter-pressure with the inflated balloon. This technique may be useful to achieve complete occlusion of TS DAVFs by endovascular means.

Endovascular management of a vein of Galen aneurysmal malformation in an infant with challenging femoral arterial access

A 5-month-old infant was to be treated with elective transarterial embolization for a vein of Galen aneurysmal malformation (VGAM). A team of endovascular surgical neuroradiologists, pediatric interventional radiologists, and pediatric cardiologists attempted conventional femoral arterial access, which was unsuccessful given the small caliber of the femoral arteries and superimposed severe vasospasm. Thereafter, eventual arterial access was achieved by navigating from the venous to the arterial system across the patent foramen ovale following a right femoral venous access. Embolization was then successfully performed. At a later date, the child underwent successful transvenous balloon-assisted embolization and eventual arterial embolization with cure of the VGAM.

Water-Borne Endovascular Embolics Inspired by the Undersea Adhesive of Marine Sandcastle Worms

Transcatheter embolization is used to treat vascular malformations and defects, to control bleeding, and to selectively block blood supply to tissues. Liquid embolics are used for small vessel embolization that require distal penetration. Current liquid embolic agents have serious drawbacks, mostly centered around poor handling characteristics and toxicity. In this work, a water-borne in situ setting liquid embolic agent is described that is based on electrostatically condensed, oppositely charged polyelectrolytes-complex coacervates. At high ionic strengths, the embolic coacervates are injectable fluids that can be delivered through long narrow microcatheters. At physiological ionic strength, the embolic coacervates transition into a nonflowing solid morphology. Transcatheter embolization of rabbit renal arteries demonstrated capillary level penetration, homogeneous occlusion, and 100% devascularization of the kidney, without the embolic crossing into venous circulation. The benign water-borne composition and setting mechanism avoids many of the problems of current liquid embolics, and provides precise temporal and spatial control during endovascular embolization.