Treatment of Visceral Artery Aneurysms Using Novel Neurointerventional Devices and Techniques

Added Value of Selective Intra-arterial Cone-Beam CT Angiography in the Management of Visceral Artery Aneurysms

PURPOSE

The aim of this study is to evaluate the value of selective intra-arterial cone-beam computed tomography angiography (CBCTA) relative to conventional computed tomography angiography (CTA) in understanding visceral artery aneurysm (VAA) morphology, and its impact on treatment planning.

MATERIALS AND METHODS

Between January 2017 and August 2021, all patients who had a diagnosis of VAA and underwent intraoperative CBCTA imaging were retrospectively reviewed. Impact on treatment decisions, optimal C-arm angulations derived from CBCTA, and additional radiation exposure were reported. Two blinded independent reviewers qualitatively reviewed CBCTA and conventional CTA images. A 5-point Likert scale (1=poor image quality, 5=excellent image quality) was used to assess the overall image quality of each modality. Number of vessels arising from the aneurysm sac was counted.

RESULTS

A total of 16 patients had a diagnosis of VAA during the study period, of whom 10 patients had intraoperative CBCTA and conventional CTA available for review. Out of 10 patients, 7 underwent successful endovascular treatment, 2 were deemed not amenable for endovascular embolization based on intraoperative CBCTA findings, and 1 had resolved pseudoaneurysm. Total fluoroscopy time and radiation dose (dose area product [DAP] and skin dose) for all procedures were 27.7 ± 19.9 minutes, 28 362 (±18 651) µGy*m2, and 1879 (±1734) mGy, respectively. Radiation exposure from CBCTA (DAP and skin dose) was 5703 (±3967) µGy*m2 and 223.6 (±141.3) mGy, respectively. In patients who underwent endovascular treatment, the proportional DAP from CBCTA was 18.3% (±15.3%) of the total procedural radiation dose. Qualitative rating of overall image quality of CBCTA images was superior to CTA images (mean score: 4.55 vs 3, p<0.001). More branch vessels arising from the VAA were identified by all reviewers in CBCTA as compared with conventional CTA (median, min-max: 3, 0-4 vs 2,1-3 vessels).

CONCLUSION

Intraoperative CBCTA after selective intra-arterial contrast injection, with better spatial resolution, provided better delineation of visceral aneurysm morphology as compared with conventional, intravenous CTA and enabled optimal treatment planning at a reasonable additional radiation exposure.

CLINICAL IMPACT

Visceral artery aneurysms (VAA) are often diagnosed incidentally by conventional computed tomographic angiography (CTA). Endovascular treatment typically requires selective angiographies at multiple projections to better understand aneurysm morphology, location, and efferent branch vessels. Intra-arterial cone-beam CT angiography (CBCTA) for VAA has the advantage of selective contrast opacification, better spatial resolution, and three-dimensional/multi-planar visualization of aneurysm morphology. In addition, CBCTA enables identification of optimal C-arm working projection for subsequent endovascular treatment. The aim of this study is to evaluate the value of intraoperative CBCTA relative to conventional CTA in understanding visceral artery aneurysm morphology and its impact on treatment planning.

CIRSE Standards of Practice for the Endovascular Treatment of Visceral and Renal Artery Aneurysms and Pseudoaneurysms

BACKGROUND

Endovascular treatment of visceral and renal artery aneurysms and pseudoaneurysms is an effective, minimally invasive treatment that has been successfully used since the early 1990s, with refined and expanded techniques and tools currently offering excellent outcomes. Due to increased detection of such lesions in recent years, many of which are asymptomatic, revision of the indications for intervention and the correct endovascular treatment approaches has become essential.

PURPOSE

This document will presume that the indication for treatment is clear and approved by the multidisciplinary team and will define the standards required for the performance of each intervention, as well as their relative advantages and limitations. CIRSE Standards of Practice documents are not intended to impose a standard of clinical patient care, but recommend a reasonable approach to, and best practices for, the performance of the endovascular treatment of visceral and renal artery aneurysms and pseudoaneurysms.

METHODS

The writing group was established by the CIRSE Standards of Practice Committee and consisted of five clinicians with internationally recognised expertise in endovascular treatments. The writing group reviewed the existing literature on visceral and renal artery aneurysms and pseudoaneurysms, performing an evidence search using PubMed to identify publications in English and relating to human subjects from 1990 to 2022. The final recommendations were formulated through consensus.

RESULTS

Endovascular treatment has an established role in the successful management of visceral and renal artery aneurysms and pseudoaneurysms, and this Standards of Practice document provides up-to-date recommendations for its safe performance.

Endovascular treatment of chronic mesenteric ischaemia secondary to a superior mesenteric artery pseudoaneurysm: a modified neurointerventional technique

A man in his late 60s presented with intermittent abdominal pain, nausea, vomiting and approximately 40 pounds of weight loss over the course of a year, most concerning for chronic mesenteric ischaemia. Given a prior negative workup, a CT angiogram was performed and revealed a wide neck mid-superior mesenteric artery pseudoaneurysm (PSA). As PSAs are susceptible to thrombus formation and distal emboli, this incidental finding was considered a possible explanation for his intermittent symptoms and thus required treatment. Anatomical constraints precluded traditional coiling or covered stent placement, so the interventional radiology team used a neurointerventional technique and performed a successful balloon-assisted coil embolisation of the PSA with subsequent resolution of the patient's symptoms. More than 3 years postprocedure, the patient remains asymptomatic with no complications.

Neuroform EZ Stents for Hepatic Artery Stenosis After Liver Transplantation: A Single-Center Preliminary Report

PURPOSE

This preliminary study evaluated the safety and effectiveness for off-label use of Neuroform EZ (NEZ) stents in the revascularization of hepatic artery stenosis (HAS) after orthotopic liver transplantation (OLT).

MATERIALS AND METHODS

Nine of 489 (5%) OLTs with HAS were managed with NEZ stents between September 2016 and July 2021. Stenting outcomes were evaluated based on the technical success rate, procedure-related complications, and primary patency.

RESULTS

A total of 10 NEZ stents (4.5 mm × 3 cm, n = 6; 4 mm × 3 cm, n = 4) were successfully deployed in 9 torturous hepatic arteries and in 1 relatively straight artery without any procedure-related complications. Combined thrombolysis (n = 3) and balloon angioplasty (n = 6) was performed. The median duration of follow-up was 438 days (range, 120-1126 days). Asymptomatic re-stenoses were detected in 2 stents on days 60 and 433 after stenting. A Kaplan-Meier curve predicted cumulative primary stent patencies at 1, 2, and 3 years of 90%, 75%, and 75%, respectively.

CONCLUSION

NEZ stents can be safely used to treat HAS after OLT with high technical success and favorable primary patency.

Endovascular repair of visceral artery aneurysms and pseudoaneurysms in 159 patients: twelve years' experience of clinical technique

OBJECTIVES

The purpose of this study was to evaluate the therapeutic efficacy and safety of endovascular treatment for patients with visceral and renal artery aneurysms (VRAAs). Twelve years of experience with interventional procedures and treatment options in our center were also worth discussing.

METHODS

From January 2009 to December 2020, clinical data of 159 consecutive patients with VRAAs were retrospectively analyzed. Patients' demographic and clinical data were recorded, and the safety and efficacy of endovascular therapy were evaluated. In addition, interventional procedures were also described.

RESULTS

A total of 159 patients underwent angiography, and 154 patients were successfully treated with endovascular therapy, with a technical success rate of 96.9%. Of the 154 patients with successful endovascular therapy, 3 patients died within 30 days of treatment, with a 30-day mortality rate of 1.9%, and the remaining patients were clinically successful, with a clinical success rate of 98.1%. Fifty-seven patients underwent emergency interventional treatment due to ruptured aneurysm. There were statistically significant differences in hemoglobin before and after emergency treatment (78.5 ± 22.0 g/dL vs. 93.8 ± 15.0 g/dL, P = 0.00). No other serious complications occurred except death in 3 patients.

CONCLUSION

Endovascular treatment of VRRAs is safe and effective and can significantly improve the symptoms of patients, especially those with ruptured aneurysms.

Evolving Diagnostic and Therapeutic Options for Visceral Artery Aneurysms

BACKGROUND

Visceral artery aneurysms (VAAs) are associated with a very high mortality rate when ruptured and may present as a surgical emergency. Due to their rarity and varying pathophysiology, literature concerning the optimal management of VAAs is limited. This review evaluates the evolving management options for VAAs with a focus on open and endovascular repair.

METHODS

A combination of databases including OVID, PubMed and Medline were used to perform a literature search. Search terms employed include 'visceral artery aneurysms', 'angiography', '3D-volumetric rendering', 'management', 'open repair' and 'endovascular repair', amongst others.

RESULTS

3D modelling in conjunction with existing diagnostic techniques, such as computed tomography and angiography, may improve diagnostic sensitivity. The literature surrounding operative management of VAAs highlights the effectiveness of endovascular repair for anatomically suitable aneurysms. Advances in endovascular technologies may expand the type and number of aneurysms amenable to catheter-based treatment approaches. For aneurysms not amenable to endovascular treatment, or those with an emergency indication, open repair remains an appropriate management choice.

CONCLUSION

Although rare, VAAs pose a high mortality risk, especially when ruptured. Practical limitations that restrict current operative approaches may be overcome by recent developments including novel neurointerventional techniques that have been applied in VAA management.

Visceral Artery Aneurysms Embolization and Other Interventional Options: State of the Art and New Perspectives

Visceral artery aneurysms (VAAs) are rare, usually asymptomatic and incidentally discovered during a routine radiological examination. Shared guidelines suggest their treatment in the following conditions: VAAs with diameter larger than 2 cm, or 3 times exceeding the target artery; VAAs with a progressive growth of at least 0.5 cm per year; symptomatic or ruptured VAAs. Endovascular treatment, less burdened by morbidity and mortality than surgery, is generally the preferred option. Selection of the best strategy depends on the visceral artery involved, aneurysm characteristics, the clinical scenario and the operator's experience. Tortuosity of VAAs almost always makes embolization the only technically feasible option. The present narrative review reports state of the art and new perspectives on the main endovascular and other interventional options in the treatment of VAAs. Embolization techniques and materials, use of covered and flow-diverting stents and percutaneous approaches are accurately analyzed based on the current literature. Visceral artery-related considerations and targeted approaches are also provided and discussed.

Experimental Analysis of Pressure and Flow Alterations During and After Insertion of a Multilayer Flow Modulator into an AAA Model with Incorporated Branch

PURPOSE

The multilayer flow modulator (MFM) device has been used for the treatment of abdominal aortic aneurysm (AAA) for over a decade. Although several clinical studies have been published, criticism and concern over the device efficacy remain, as no quantitative analysis that describes its mechanism has been performed yet. The aim of this study was to experimentally evaluate the effect of MFM device deployment on aneurysmal pressure and branch perfusion.

MATERIALS AND METHODS

An experimental flow and pressure monitoring system was developed to analyze the MFM deployment procedure performed by a qualified radiologist in AAA geometries with and without side branch. Particle image velocimetry experiments were then conducted on models with and without MFM device to evaluate and compare flow patterns and local flow velocity and vorticity in the aneurysm.

RESULTS

The experiments revealed no significant change in pressure and flow rate during and after deployment of the MFM device. The flow rate of the incorporated branch was fully preserved. On both models, the aneurysmal flow velocity was significantly reduced. In addition, the device modified local flow patterns, reducing vorticity and better feeding the incorporated branch.

CONCLUSION

This experimental study provides the basis for a better understanding of the mechanism of the MFM device, which allows intra-aneurysmal flow to decrease while preserving incorporated branch flow and reducing the risk of type II endoleak. The experimental system developed for this study was effective in simulating an endovascular procedure and studying the safety and effectiveness of endovascular devices.

Retreatment of a recanalized splenic artery aneurysm using a low-profile microembolization platform

Recanalization of a splenic artery aneurysm owing to incomplete transcatheter coil embolization is uncommon. In addition to the challenges of inherent vessel tortuosity, reintervention via catheterization of the main splenic artery presents unique difficulties in navigating across potentially obstructive preexisting coils. We describe here the application of a low-profile microembolization platform, most commonly used in neurovascular interventions, in the treatment of a tortuous, expanding splenic artery aneurysm that had previously undergone failed coil embolization.

Treatment of visceral artery aneurysms and pseudoaneurysms with the use of cerebral flow diverting stents: initial experience

Background

Flow-diverter stents (FDS) are designed to maintain laminar flow in the parent artery and sidebranches and to promote thrombosis of the aneurysm. Although these devices were developed for use in intracranial circulation, FDS could be employed to treat aneurysms regardless of their location, when anatomic factors may limit the efficacy of classic endovascular techniques. The objective of this study is to describe the initial experience of a single center in the treatment of visceral artery aneurysms and pseudoaneurysms (VAA-VAP) with cerebral FDS, analyzing safety, efficacy and 1-year outcome. Between 2016 and 2018 six patients (4 women, mean age 57.6) underwent treatment with FDS of 4 VAA and 2 VAP located in renal (4), hepatic (1) and splenic arteries (1). Mean aneurysm diameter was 14.3 mm (range 8–22). All the aneurysms had sidebranches arising from the neck or had an unfavorable dome-to-neck ratio. Technical success, safety, efficacy and 1-year outcome were analyzed. Follow-ups (FU) with Color-Doppler US and CTA ranged from 12 to 36 (mean 20) months.

Results

Technical success was achieved in all cases. There were no aneurysm rupture nor reperfusion after exclusion. Five out of six (83.3%) FDS were patent at each FU; all the aneurysms showed shrinkage with a mean dimensional reduction rate of 55.8%. Sac thrombosis was observed in 4 aneurysms at 1 (n = 3) and at 12-month FUs. There was one sidebranch occlusion with evidence of a small area of kidney hypoperfusion at the 12-month FU, which was asymptomatic. In one patient, a reintervention was needed because CTA showed a severe in-stent stenosis, which was symptomatic. Mean hospitalization was 4.1 days.

Conclusions

Treatment of morphologically complex VAA and VAP with cerebral FDS proved to be safe and efficient. Stronger evidence from larger populations are required.

Contemporary endovascular management of splenic vascular pathologies

The spleen is a commonly injured organ and the splenic vasculature is also susceptible to inflammation and trauma, often resulting in aneurysm formation. Splenic artery aneurysms carry a high risk of rupture and are associated with high mortality and morbidity. Due to the advances in endovascular techniques and devices, endovascular management of splenic vascular pathologies is now considered a first-line strategy. Endovascular embolisation and advance techniques including balloon- or stent-assisted coil embolisation enables minimally invasive management option while preserving splenic function.

Elective Embolization of Splenic Artery Aneurysms with an Ethylene Vinyl Alcohol Copolymer Agent (Squid) and Detachable Coils

PURPOSE

To report the safety and efficacy of the embolization of splenic artery aneurysms (SAAs) with coils plus ethylene vinyl alcohol copolymer (EVOH) agent.

MATERIALS AND METHODS

A single-center retrospective study was conducted from 2016 to 2019 to collect SAAs. Twelve asymptomatic patients (mean age, 59 years) with 15 SAAs (mean size, 23.6 mm; size range, 15-40 mm) were treated with embolization. Embolization was performed with EVOH (Squid 8/34) and fibered detachable coils. Transfemoral embolization was performed with a microcatheter to achieve a splenic artery occlusion embolizing the SAA and its efferent and afferent branches. Follow-up was based on color Doppler ultrasound at 24 hours and on computed tomography (CT) angiography at 1 (n = 12) and 6 months (n = 12) after embolization. Mean number of coils and Squid vials used for each patient, major/minor complications, technical success, 30-day clinical success, cases of revascularization/reintervention, and mortality were assessed. Technical success was defined as complete exclusion of the aneurysmal segment and cessation of blood flow into the sac. Clinical success at 1 month was based on the absence of clinical symptoms and the exclusion of aneurysm revascularization on CT angiography.

RESULTS

The mean number of coils and Squid vials was 5.75 (standard deviation [SD], 1.58; range, 3-9) and 1.41 (SD, 0.49; range, 1-2), respectively. Both technical and 30-day clinical success were 100%, with no cases of aneurysm revascularization (CT angiography performed in all patients at 1 month and 6 months and in 3 patients at 24 months). No major complications or fatal events were recorded. In terms of minor complications, 2 cases of mild pancreatitis (transient amylases increase) and 1 case of focal splenic ischemia without clinical sequelae were recorded.

CONCLUSIONS

Embolization in SAAs using coils plus EVOH was safe and effective without SAA revascularization.

Ultrasmall BiOI Quantum Dots with Efficient Renal Clearance for Enhanced Radiotherapy of Cancer

Emerging strategies involving nanomaterials with high-atomic-number elements have been widely developed for radiotherapy in recent years. However, the concern regarding their potential toxicity caused by long-term body retention still limits their further application. In this regard, rapidly clearable radiosensitizers are highly desired for practical cancer treatment. Thus, in this work, ultrasmall BiOI quantum dots (QDs) with efficient renal clearance characteristic and strong permeability inside solid tumor are designed to address this issue. Additionally, considering that injection methods have great influence on the biodistribution and radiotherapeutic efficacy of radiosensitizers, two common injection methods including intratumoral injection and intravenous injection are evaluated. The results exhibit that intratumoral injection can maximize the accumulation of radiosensitizers within a tumor compared to intravenous injection and further enhance radiotherapeutic efficacy. Furthermore, the radiosensitizing effect of BiOI QDs is revealed, which is not only attributed to the radiation enhancement of high-Z elements but also is owed to the •OH production via catalyzing overexpressed H2O2 within a tumor by BiOI QDs under X-ray irradiation. As a result, this work proposes a treatment paradigm to employ ultrasmall radiosensitizers integrated with local intratumoral injection to realize rapid clearance and high-efficiency radiosensitization for cancer therapy.

Hepatic artery stenosis angioplasty and implantation of Wingspan neurovascular stent: A case report and discussion of stenting in tortuous vessels

BACKGROUND

Hepatic artery stenosis is a complication of orthotopic liver transplant occurring in 3.1%-7.4% of patients that can result in graft failure and need for re-transplantation. Endovascular therapy with angioplasty and stenting has been used with a high degree of technical success and good clinical outcomes, but tortuous hepatic arteries present a unique challenge for intervention. Suitable stents for this application should be maneuverable and conformable while also exerting adequate radial force to maintain a patent lumen.

CASE SUMMARY

Herein we report our experience with a neurovascular Wingspan stent system in a challenging case of recurrent hepatic artery stenosis and discuss the literature of stenting in tortuous transplant hepatic arteries.

CONCLUSION

Wingspan neurovascular stent is self-expanding, has good conformability, and adequate radial resistance and as such it could be added to the armamentarium of interventionalists in the setting of a tortuous and stenotic transplant hepatic artery.