Arterio-venous malformation: how much do we know?

Oscillatory shear stress modulates Notch-mediated endothelial mesenchymal plasticity in cerebral arteriovenous malformations

BACKGROUND

Cerebral arteriovenous malformations (cAVM) are a significant cause of intracranial hemorrhagic stroke and brain damage. The arteriovenous junctions in AVM nidus are known to have hemodynamic disturbances such as altered shear stress, which could lead to endothelial dysfunction. The molecular mechanisms coupling shear stress and endothelial dysfunction in cAVMs are poorly understood. We speculated that disturbed blood flow in artery-vein junctions activates Notch receptors and promotes endothelial mesenchymal plasticity during cAVM formation.

METHODS

We investigated the expression profile of endothelial mesenchymal transition (EndMT) and cell adhesion markers, as well as activated Notch receptors, in 18 human cAVM samples and 15 control brain tissues, by quantitative real-time PCR (qRT-PCR) and immunohistochemical evaluation. Employing a combination of a microfluidic system, qRT-PCR, immunofluorescence, as well as invasion and inhibitor assays, the effects of various shear stress conditions on Notch-induced EndMT and invasive potential of human cerebral microvascular endothelial cells (hCMEC/d3) were analyzed.

RESULTS

We found evidence for EndMT and enhanced expression of activated Notch intracellular domain (NICD3 and NICD4) in human AVM nidus samples. The expression of transmembrane adhesion receptor integrin α9/β1 is significantly reduced in cAVM nidal vessels. Cell-cell adhesion proteins such as VE-cadherin and N-cadherin were differentially expressed in AVM nidus compared with control brain tissues. Using well-characterized hCMECs, we show that altered fluid shear stress steers Notch3 nuclear translocation and promotes SNAI1/2 expression and nuclear localization. Oscillatory flow downregulates integrin α9/β1 and VE-cadherin expression, while N-cadherin expression and endothelial cell invasiveness are augmented. Gamma-secretase inhibitor RO4929097, and to a lesser level DAPT, prevent the mesenchymal transition and invasiveness of cerebral microvascular endothelial cells exposed to oscillatory fluid flow.

CONCLUSIONS

Our study provides, for the first time, evidence for the role of oscillatory shear stress in mediating the EndMT process and dysregulated expression of cell adhesion molecules, especially multifunctional integrin α9/β1 in human cAVM nidus. Concomitantly, our findings indicate the potential use of small-molecular inhibitors such as RO4929097 in the less-invasive therapeutic management of cAVMs.

Case Report: A Rare Abdominopelvic Arteriovenous Malformation: Originating From Splenic Artery and Draining Into Portal Vein

Background

Abdominopelvic arteriovenous malformation is an uncommon congenital vascular lesion, for which the diagnosis and treatment are usually difficult. Though embolization and sclerotherapy are the primary treatment strategies, traditional surgical resection remains a valuable option.

Case Presentation

Herein, we present a 32-year-old female diagnosed with a massive abdominopelvic arteriovenous malformation that originates from the splenic artery and drains into the portal vein. The vascular lesion was evaluated with multiple imaging modalities and then surgically resected successfully. The patient was discharged post-operatively on day 6 and free of symptoms during the 12-month follow-up.

Conclusion

To our knowledge, the presented abdominopelvic arteriovenous malformation is the first to be reported in the literature, with such a rare condition originating from the splenic artery and draining into the portal vein.

A Computational Framework for Pre-Interventional Planning of Peripheral Arteriovenous Malformations

PURPOSE

Peripheral arteriovenous malformations (pAVMs) are congenital lesions characterised by abnormal high-flow, low-resistance vascular connections-the so-called nidus-between arteries and veins. The mainstay treatment typically involves the embolisation of the nidus, however the complexity of pAVMs often leads to uncertain outcomes. This study aims at developing a simple, yet effective computational framework to aid the clinical decision making around the treatment of pAVMs using routinely acquired clinical data.

METHODS

A computational model was developed to simulate the pre-, intra-, and post-intervention haemodynamics of a patient-specific pAVM. A porous medium of varying permeability was employed to simulate the sclerosant effect on the nidus haemodynamics. Results were compared against clinical data (digital subtraction angiography, DSA, images) and experimental flow-visualization results in a 3D-printed phantom of the same pAVM.

RESULTS

The computational model allowed the simulation of the pAVM haemodynamics and the sclerotherapy-induced changes at different interventional stages. The predicted inlet flow rates closely matched the DSA-derived data, although the post-intervention one was overestimated, probably due to vascular system adaptations not accounted for numerically. The nidus embolization was successfully captured by varying the nidus permeability and increasing its hydraulic resistance from 0.330 to 3970 mmHg s ml-1. The nidus flow rate decreased from 71% of the inlet flow rate pre-intervention to 1%: the flow completely bypassed the nidus post-intervention confirming the success of the procedure.

CONCLUSION

The study demonstrates that the haemodynamic effects of the embolisation procedure can be simulated from routinely acquired clinical data via a porous medium with varying permeability as evidenced by the good qualitative agreement between numerical predictions and both in vivo and in vitro data. It provides a fundamental building block towards a computational treatment-planning framework for AVM embolisation.

Surgical management of auricular arteriovenous malformations: A literature review

Auricular arteriovenous malformations (AVMs) can cause a variety of symptoms that seriously impact the patient's appearance, life, and mental well‐being. Surgery is the primary management method for auricular AVMs, but there is no consensus on how to surgically manage auricular AVMs. In this article, we document a comprehensive review of the characteristics, classification, and surgical interventions to treat auricular AVMs.

Quality of life and mental health of patients with vascular malformations in a single specialist center in the United Kingdom

OBJECTIVE

Patients with vascular malformations suffer from chronic debilitating symptoms that have been shown to contribute negatively to their quality of life (QoL) and mental health. Despite this, the current literature evaluating the QoL and mental health of patients with vascular malformations remains scarce. Our aim was to evaluate the QoL and mental health of patients with vascular malformations.

METHODS

We prospectively analyzed the validated health-related QoL (HRQoL) questionnaires: the RAND Health Care 36-Item Short Form Survey (SF-36), Hospital Anxiety and Depression Scale (HADS), and visual analogue score for pain reported by 253 patients with vascular malformations in a specialist center of vascular anomalies in the UK over two years.

RESULTS

Patients with vascular malformations reported significantly poorer SF-36 scores in all domains compared with the UK general population. Patients with low-flow vascular malformations and arteriovenous malformations reported little variations in SF-36, HADS, and visual analogue score for pain scores. No significant association was found between age and any of the health-related QoL scores, other than the physical functioning in SF-36. Female patients reported significantly lower physical and social functioning of SF-36 and worse HADS-Depression than their male counterparts. Patients with syndromic vascular malformations reported significantly lower SF-36 scores in role-physical, role-emotional and bodily pain than nonsyndromic vascular malformations.

CONCLUSIONS

This study concluded that patients with vascular malformations reported worse QoL than the UK general population. Therefore, the assessment and management of QoL and mental health should be incorporated into the overall treatment strategies of patients with vascular malformations.

Endovascular approach for arteriovenous limb malformations: a single center experience

BACKGROUND

To assess imaging findings, describe endovascular technical aspects and analyzed procedural outcomes in a population of patients underwent limb arteriovenous malformation (LAVMs).

METHODS

From January 2015 to December 2018, all consecutive patients underwent an endovascular procedure for ICD-9-CM codex for arteriovenous malformation problems were retrospective reviewed. Among these, patients with LAVMs were selected. Demographic, preoperative imaging, interventional and postprocedural data were collected for each patient and procedure. The International Society of Vascular Anomalies, the Cho-Do angiographic classification and the Schobinger clinical stage were used to describe disease type, aspect and clinical severity. Angiographic and clinical outcomes were also described.

RESULTS

During the study period, 76 intervention for AVMs were performed in 52 patients. Among these, 26 LAVMs were selected and analyzed in 21 patients (number of LAVMs per patient: 1.2±0.5), 14 affecting upper limbs, 17 lower limbs. Pain, discomfort and swelling were main symptoms reported (95%, 90% and 62%, respectively). Ultrasound scan, computed angiography tomography and magnetic resonance angiography were used - alone or in combination - as preoperative imaging in 67%, 62% and 48% of patients, respectively. Cho-Do class ≥3 was described in 70% of treated LAVMs and a Schobinger stage ≥2 in more than 90%. Ipsilateral femoral access with a 5F introducer was preferred. Selective embolization with glue was the most preferred technique (57%), in combination or not with microsphere embolization (19%) and/or direct nidus sclerotherapy (14%). Optimal and suboptimal results were achieved in 86% of cases. Further interventions were performed in 52% of cases, with more than two interventions in 29% of cases.

CONCLUSIONS

Quality of life, clinical picture and anatomical structure are items of paramount importance during preoperative LAVMs endovascular treatment planning. Treatment must be focused on LAVMs type, minimizing invasiveness and number of interventions, although secondary intervention rate remains quite high.

Treatment Outcomes of Embolization for Peripheral Arteriovenous Malformations

PURPOSE

To evaluate treatment outcomes of embolization for peripheral arteriovenous malformations (AVMs) in a tertiary referral center where ethanol is the primary agent of choice.

METHODS

A 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.

RESULTS

In 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.

CONCLUSIONS

AVM 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.

Dynamic Brow Restoration Using a Soft Tissue Expander in Adult Patients With Arteriovenous Malformation

BACKGROUND

Impaired brow function in adult patients with arteriovenous malformation is a serious disability that can even influence the field of vision. Brow reanimation techniques are used to recover a more natural appearance and brow function. Many static procedures have been set to augment brow elevation, but only dynamic procedures can lead to better functional results. In this study, the experience of a single surgeon addressing the challenge of brow restoration with dynamic procedures is presented.

METHODS

A retrospective review was performed using the records of 4 adult patients who underwent dynamic procedures using a soft tissue expander for brow restoration after arteriovenous malformation excision in the unilateral site of the forehead with the expander on the contralateral side. Movement and electrodiagnostic examinations were performed postoperatively at 2 months.

RESULTS

The patients included 3 males and 1 female (mean age, 20.5 ± 4.04 years). Brow improvement was noted in all patients. The results of the electrodiagnostic examination showed synchronous and spontaneous motor unit potentials and compound muscle action potentials with the contralateral forehead.

CONCLUSIONS

Dynamic procedures using a soft tissue expander can provide both static and dynamic functional brow elevation of the contralateral frontalis and skin.

Endovascular Management of a Giant High-Flow Lower Limb Arteriovenous Malformation

PURPOSE

High-flow arteriovenous malformations (AVMs) may pose a challenge for endovascular treatment due to high-flow rates. Incomplete treatment, recurrence, or even worsening can occur if a proper management is not performed. We report a case successfully treated with endovascular therapy.

CASE REPORT

A 37-year-old male was referred to our hospital with a soft tumor in the left thigh, limb asymmetry and associated pain. Doppler ultrasound and magnetic resonance imaging showed an extensive high-flow AVM with a venous aneurysm of 40 mm diameter. Diagnostic angiography identified multiple feeding vessels from the profunda femoris and superficial femoral arteries. Two endovascular interventions were performed within 1 month, combining afferent vessel embolization and percutaneous thrombin injection into the nidus, to exclude the AVM. Two-year imaging follow-up revealed thrombosis of the malformation. The patient remained asymptomatic with normal thigh diameter. No complications were documented in any of the sessions.

CONCLUSION

Endovascular therapy could be a safe and effective option for AVM as long as it includes not only feeding vessels embolization but also complete occlusion of the nidus.

A Diagnostic Program of Vascular Tumor and Vascular Malformations in Children According to Modern Classification

The aim of the study was to analyze the cohort of inpatient children with vascular anomalies according to the globally accepted classification introduced by the ISSVA.

METHODS

The study included 205 inpatient children within the time period of the years 2010-2015. Types of vascular anomalies (VAs), age of patients, diagnostic procedures, and anatomical localization of VAs were analyzed.

RESULTS

65 patients of first year of life had vascular tumors, with prevalence of infantile hemangiomas (IHs) in 57 (87.7%) patients. 45 children had IHs localized within soft tissues, whereas 7 patients suffered from IHs of the liver, and 5 children from IHs of the respiratory tract. Most patients with soft tissue IHs were diagnosed only with ultrasound; СT or MRI diagnostics were performed on 5 (8.8%) patients, and biopsy was carried out in 2 (4.4%) children. Vascular malformations (VM) were diagnosed in 140 (68.3%) patients. Ultrasound investigation (US) was the screening method. MRI was performed to confirm the diagnosis of low-flow VM, whereas for high-flow VM CT angiography and selective angiography were useful. Venous malformations were diagnosed in 17 (12.1%) patients, and 112 (80.0%) had cystic LM, among them children under the age of 2 years prevailed. Arteriovenous malformations were diagnosed in 5 (3.8%) patients, ages 2-14 years.

CONCLUSIONS

Clinical manifestations of vascular anomalies have clear age features. Among hospitalized children vascular tumors add up to 31.7% and VM - up to 68.3%.

Vascular anomalies: A pictorial review of nomenclature, diagnosis and treatment

Vascular anomalies, including vascular malformations and tumors, are frequently straightforward to detect; however, accurate diagnosis and appropriate treatment are often challenging. Misdiagnosis of these lesions can lead clinicians in the wrong direction when treating these patients, which can have unfavorable results. This review presents an overview of the classification systems that have been developed for the diagnosis of vascular lesions with a focus on the imaging characteristics. Pictorial examples of each lesion on physical examination, as well as non-invasive and minimally invasive imaging are presented. An overview of the endovascular treatment of these lesions is also given. In some cases, vascular anomalies may be associated with an underlying syndrome and several of the most commonly encountered syndromes are discussed. Understanding of the classification systems, familiarity with the treatment options and knowledge of the associated syndromes are essential for all physicians working with this patient population. The approach to the described entities necessitates an organized multi-disciplinary team effort, with diagnostic imaging playing an increasingly important role in the proper diagnosis and a combined interventional radiologic and surgical treatment method showing promising results.

Endovascular embolization of a muscular symptomatic arteriovenous malformation with Glubran 2 acrylic glue

OBJECTIVE

Few cases of muscle arteriovenous malformations have been reported in literature to date.

CASE REPORT

We report the case of a 32-year-old man presenting a muscle arteriovenous malformation involving the vastus lateralis muscle with recurrent episodes of pain. The patient was treated by transcatheter embolization with Glubran 2 acrylic glue. There were no periprocedural or subsequent clinical complications, the glue resulted in successful selective occlusion and the patient showed resolution of symptoms at the six-months follow-up.

CONCLUSIONS

Endovascular therapy has been shown to be beneficial in patients with high surgical risks and is the treatment of choice for arteriovenous malformation lesions that extend beyond the deep fascia and involve muscle, tendon, and bone. Glubran 2 constitutes a useful tool to attempt embolization of the muscle arteriovenous malformation nidus, with easier handling and promising results.

Vascular anomalies: classification, imaging characteristics and implications for interventional radiology treatment approaches

The term vascular anomaly represents a broad spectrum of vascular pathology, including proliferating vascular tumours and vascular malformations. While the treatment of most vascular anomalies is multifactorial, interventional radiology procedures, including embolic therapy, sclerotherapy and laser coagulation among others, are playing an increasingly important role in vascular anomaly management. This review discusses the diagnosis and treatment of common vascular malformations, with emphasis on the technique, efficacy and complications of different interventional radiology procedures.

Venous malformation and haemangioma: differential diagnosis, diagnosis, natural history and consequences

Venous malformation (VM) is the most common form of congenital vascular malformation (CVM). VM presents at birth as an inborn vascular defect and never disappears/regresses spontaneously through the rest of life; it will continue to grow slowly at a rate that is proportional to the growth rate of the body. Haemangioma is not a vascular malformation but one of the vascular tumours originating from the endothelial cells; it develops after birth mostly in the infantile/neonatal period with a distinctive growth cycle: a proliferation phase of early rapid growth followed by an involutional phase of slow regression. Although the vascular malformation and vascular tumour belong to the ‘vascular anomaly’ together, both conditions are fundamentally different not only in their anatomical, histological and pathophysiological findings but also in their clinical courses. Therefore, an appropriate differential diagnosis of the VM is mandated not only from other kinds of CVMs but also from ‘genuine’ haemangioma. Appropriate diagnosis and assessment of VMs can be made based on clinical presentation and a proper combination of basic non-invasive studies in general but the presence of a mixed lesion involving other types of CVM lesions and the type of VM lesion, extratruncular and truncular, will dictate the need for further work-up with additional non- to less-invasive study or angiography. Otherwise, angiography is usually reserved for therapeutic planning and treatment.

Intraosseous Venous Malformations of the Facial Bone: A Retrospective Study in 11 Patients

Objectives:

To investigate the clinical symptoms, computed tomography (CT) features and treatments of intraosseous venous malformations (IVM) that occur in the facial bone.

Methods and Results:

Eleven patients with facial IVM were treated with two surgical techniques, excision ( n = 4) or curettage ( n = 7). No recurrence was encountered at follow-up (45.8 ± 16.0 months). Postoperative deformities were left in two paediatric patients who were treated with excision.

Conclusions:

The diagnosis of IVM can be difficult and is mainly based on clinical symptoms and CT features. IVM should be differentiated from other lesions, including ameloblastoma, odontogenic cysts, osteosarcoma, aneurysmal bone cysts and arteriovenous malformations, among others. Conventional block biopsy should be replaced by fine needle aspiration cytology for further diagnosis. Curettage is a more appropriate method for IVM compared with excessive en-bloc osteotomy, while transosseous embolo-sclerotherapy may be a promising alternative method. Finally, the terminological confusion between ‘intraosseous haemangioma’ and ‘intraosseous venous malformation’ should be avoided according to the binary classification.

Endovascular approaches to arteriovenous fistula

AVFs differ in their characteristics, natural history, and response to interventions. These differences need to be considered when planning treatment. Endovascular treatments have emerged as a mainstay of treatment of all types of AVMs. They can be used as definitive therapy for acquired arteriovenous malformation, in remote or high-risk locations, and in elderly or otherwise debilitated patients. Endovascular control is often helpful in open repair of acquired AVF. Endovascular techniques are essential in the management of congenital AVF and are the first line of interventional therapy. In these cases, repeated interventions are the rule, and careful imaging and planning is the key to success.