Spetzler-Martin Grade III Arteriovenous Malformations: A Comparison of Modified and Supplemented Spetzler-Martin Grading Systems.

BACKGROUND: The modified Spetzler-Martin (SM) grading system proposes that grade III arteriovenous malformation (AVM) subtypes are associated with variable microsurgical risks, with small AVMs (III-) having lower risk and medium/eloquent AVMs (III+) having higher risk. Adding patient age and AVM bleeding status and compactness to the SM grade produces a score - the supplemented SM (Supp-SM) grade - to more accurately assess preoperative risk. OBJECTIVE: To compare the predictive power of the modified SM and Supp-SM grades for risk assessment in patients with grade III AVMs. METHODS: Patients with SM grade III AVMs treated between 2011 and 2018 were retrospectively reviewed. Good outcomes were defined as modified Rankin Scale (mRS) scores ≤ 2 or unchanged/improved mRS scores (pre- vs postsurgery). RESULTS: Of 102 patients with SM grade III AVMs, 59% had grade III- and 24% had grade III+ AVMs. Supp SM grade 6 and grade 7 AVMs accounted for 44% and 24%, respectively. Overall, 33% of patients worsened but outcomes did not significantly differ by SM III subtype. Neurological outcomes were associated with Supp-SM grade, with proportions of patients with worsening increasing from 0% with Supp-SM grade 4 AVMs to 54% with Supp-SM grade 7 AVMs. Analyses of factors associated with neurological worsening identified age > 60 yr and Supp-SM grade 7 as significant. CONCLUSION: Supp-SM grades were more predictive of microsurgical outcomes than modified SM grades for grade III AVMs, with a hard cutoff for acceptable surgical risk at Supp-SM grade 6. Supp-SM grading is a better decision-making tool than subtyping with the modified SM scale.

Machine Learning Classification for Assessing the Degree of Stenosis and Blood Flow Volume at Arteriovenous Fistulas of Hemodialysis Patients Using a New Photoplethysmography Sensor Device.

The classifier of support vector machine (SVM) learning for assessing the quality of arteriovenous fistulae (AVFs) in hemodialysis (HD) patients using a new photoplethysmography (PPG) sensor device is presented in this work. In clinical practice, there are two important indices for assessing the quality of AVF: the blood flow volume (BFV) and the degree of stenosis (DOS). In hospitals, the BFV and DOS of AVFs are nowadays assessed using an ultrasound Doppler machine, which is bulky, expensive, hard to use, and time consuming. In this study, a newly-developed PPG sensor device was utilized to provide patients and doctors with an inexpensive and small-sized solution for ubiquitous AVF assessment. The readout in this sensor was custom-designed to increase the signal-to-noise ratio (SNR) and reduce the environment interference via maximizing successfully the full dynamic range of measured PPG entering an analog-digital converter (ADC) and effective filtering techniques. With quality PPG measurements obtained, machine learning classifiers including SVM were adopted to assess AVF quality, where the input features are determined based on optical Beer-Lambert's law and hemodynamic model, to ensure all the necessary features are considered. Finally, the clinical experiment results showed that the proposed PPG sensor device successfully achieved an accuracy of 87.84% based on SVM analysis in assessing DOS at AVF, while an accuracy of 88.61% was achieved for assessing BFV at AVF.

Angioarchitecture and hemodynamics of microvascular arterio-venous malformations.

INTRODUCTION: Arteriovenous malformations (AVMs) are characterized by pathological high flow, low resistance connections between arteries and veins. Treatment is critically dependent on correct interpretation of angioarchitectural features. However, some microfistular AVMs do not match the characteristics described in current AVM classification systems. Therefore, we propose a new subgroup of microfistular AVMs, composed of enlarged, fistulous paths on the venous half of capillaries and/or dilated draining venules (hyperdynamic, capillary-venulous malformation [CV-AVM]). CV-AVMs still ensure arterial flow to the periphery and fistulous venous drainage is less pronounced than in classical AVMs such that these lesions are often misinterpreted as venous malformations. MATERIALS AND METHODS: We developed a computational model to study the effects of microvascular anomalies on local hemodynamics, as well as their impact on angiographic contrast propagation. Flow rates and pressures were computed with a lumped parameter description, while contrast propagation was determined by solving the 1D advection-diffusion equation. RESULTS AND CONCLUSIONS: For the newly proposed CV-AVM angioarchitecture, the computational model predicts increased arterio-venous contrast agent transit times and highly dispersive transport characteristics, compared to microfistular, interstitial type IV AVMs and high flow type II and III AVMs. We related these findings to time-contrast intensity curves sampled from clinical angiographies and found that there is strong evidence for the existence of CV-AVM.

Levenberg-Marquardt Neural Network Algorithm for Degree of Arteriovenous Fistula Stenosis Classification Using a Dual Optical Photoplethysmography Sensor.

This paper proposes a noninvasive dual optical photoplethysmography (PPG) sensor to classify the degree of arteriovenous fistula (AVF) stenosis in hemodialysis (HD) patients. Dual PPG measurement node (DPMN) becomes the primary tool in this work for detecting abnormal narrowing vessel simultaneously in multi-beds monitoring patients. The mean and variance of Rising Slope (RS) and Falling Slope (FS) values between before and after HD treatment was used as the major features to classify AVF stenosis. Multilayer perceptron neural networks (MLPN) training algorithms are implemented for this analysis, which are the Levenberg-Marquardt, Scaled Conjugate Gradient, and Resilient Back-propagation, to identify the degree of HD patient stenosis. Eleven patients were recruited with mean age of 77 ± 10.8 years for analysis. The experimental results indicated that the variance of RS in the HD hand between before and after treatment was significant difference statistically to stenosis (p < 0.05). Levenberg-Marquardt algorithm (LMA) was significantly outperforms the other training algorithm. The classification accuracy and precision reached 94.82% and 92.22% respectively, thus this technique has a potential contribution to the early identification of stenosis for a medical diagnostic support system.

Caso de desafío diagnóstico: fístula dural / Diagnostic challenge case: dural fistula

Se presenta el caso de una paciente de sexo femenino, de 69 años, que refiere tinnitus pulsátil de dos meses de evolución percibido en la región retroauricular derecha. Se presentan los hallazgos en estudios de imágenes, diagnóstico y se presenta una corta revisión del tema.

We present the case of a female patient, 69 years old, who reported pulsatile tinnitus since two months ago perceived in the right retroauricular region. We present the findings in image studies, diagnosis and a short review about the topic.

Modern classification and outcome predictors of surgery in patients with brain arteriovenous malformations.

Brain arteriovenous malformations (bAVM) are challenging lesions. Part of this challenge stems from the infinite diversity of these lesions regarding shape, location, anatomy, and physiology. This diversity has called on a variety of treatment modalities for these lesions, of which microsurgical resection prevails as the mainstay of treatment. As such, outcome prediction and managing strategy mainly rely on unraveling the nature of these complex tangles and ways each lesion responds to various therapeutic modalities. This strategy needs the ability to decipher each lesion through accurate and efficient categorization. Therefore, classification schemes are essential parts of treatment planning and outcome prediction. This article summarizes different surgical classification schemes and outcome predictors proposed for bAVMs.

Paraspinal arteriovenous fistula: Stuttgart classification based on experience and a review of the literature.

The term "paraspinal arteriovenous shunts" (PAVSs) summarizes an inhomogeneous variety of rare vascular disorders. PAVSs have been observed as congenital or acquired lesions. The clinical course of PAVSs may be asymptomatic or present with life-threatening symptoms. Based on a collection of individual cases from three institutions and a literature evaluation, we propose the following classification: PAVSs that are part of a genetic syndrome are separated from "isolated" PAVSs. Isolated PAVSs are subdivided into "acquired", "traumatic" and "congenital" without an identifiable genetic hereditary disorder. The subgroups are differentiated by the route of venous drainage, being exclusively extraspinal or involving intraspinal veins. PAVSs associated to a genetic syndrome may either have a metameric link or occur together with a systemic genetic disorder. Again extra-vs intraspinal venous drainage is differentiated. The indication for treatment is based on individual circumstances (e.g. myelon compression, vascular bruit, high volume output cardiac failure). Most PAVSs can be treated by endovascular means using detachable coils, liquid embolic agents or stents and derivates.

Persistent Pulmonary Arteriovenous Malformations: Percutaneous Embolotherapy.

Pulmonary arteriovenous malformations (PAVM) are an uncommon entity that interventional radiologists may face in their clinical practice. Many of these lesions are treated successfully using endovascular techniques with satisfactory long-term results. However, some PAVMs respond poorly to initial interventional techniques. This article reviews the signs and symptoms of persistent PAVMs, illustrates different imaging modalities used to diagnose these lesions, and outlines mechanisms by which these lesions may persist. The article highlights techniques and embolic agents used for percutaneous transcatheter embolotherapy of persistent PAVMs and discuss the outcomes of these interventions.

Utilidad del mapeo ecográfico preoperatorio para los accesos vasculares de hemodiálisis / Use of pre-operative ultrasound mapping for haemodialysis vascular access

OBJETIVOS: Valorar la utilidad clínica de la introducción rutinaria del mapeo ecográfico de extremidades superiores en el estudio preoperatorio de los pacientes candidatos a un acceso vascular (AV) para hemodiálisis. MATERIAL Y MÉTODOS: Estudio unicéntrico retrospectivo de 4 años de duración. Incluimos pacientes con enfermedad renal crónica terminal (ERCT) candidatos a un AV para hemodiálisis, excluyendo a aquellos con fístulas arteriovenosas (FAV) previas en la misma extremidad superior. Dos grupos de estudio: exploración física (EF: junio de 2011-febrero de 2014) y mapeo ecográfico (ECO: marzo de 2014-junio de 2015). Analizamos: variables demográficas, comorbilidad y tipo de AV. En el subgrupo FAV radiocefálicas, analizamos la tasa de permeabilidad inmediata (48 h), precoz (4 semanas), tardía (6 meses) y los procedimientos realizados. RESULTADOS: Estudiamos a 81 pacientes (EF: 42; ECO: 39), de los que el 63% eran hombres, con una edad media de 66,5±13,1 años. El 81% fueron izquierdos. No se evidenciaron diferencias significativas entre los grupos respecto a demografía, comorbilidad ni etiología de la ERCT. Tipo de AV (EF vs. ECO): FAVRC* (47,6 vs. 69,2%; *p < 0,05); húmero-cefálicas* (38,1 vs. 10,3%); húmero-basílicas (11,9 vs. 17.9%) y prótesis húmero-axilares (2,4 vs. 2,6%). Tasa de permeabilidad FAV radiocefálicas: inmediata (90 vs. 85,2%); precoz (75 vs. 100%*) y tardía (55 vs. 88,9%*), respectivamente. Solo observamos un mayor número de AV realizados en otros territorios (25 vs. 3,7%*) en el grupo EF de las FAV radiocefálicas. CONCLUSIONES: En nuestro centro, la introducción rutinaria del mapeo ecográfico de las extremidades superiores en el estudio preoperatorio de los pacientes candidatos a un AV permitió optimizar el territorio vascular distal y mejorar la permeabilidad precoz y tardía de las fístulas radiocefálica

OBJECTIVES: To assess the clinical usefulness of routine doppler ultrasound vascular mapping of upper extremities before creating a vascular access (VA) for haemodialysis. MATERIAL AND METHODS: A retrospective single-centre study conducted over a four-year period including end-stage renal disease (ESRD) patients referred to for VA creation for haemodialysis. Patients with previous VA in the same upper extremities were excluded. Two study groups were formed: Physical examination (PE: June 2011-February 2014) and ultrasound mapping (US: March 2014-June 2015). An analysis was performed on the demographic variables, comorbidities and AV location. The results of the patency rates of the radio-cephalic fistulae (RCF) subgroup were recorded, immediately (48 h), early (4 weeks), and late (6 months). RESULTS: The study included a total 81 patients (42 PE, 39 US), with 63% males. The mean age was 66.5±13.1 years, and 81% were affected on the left side. There were no significant differences between the groups as regards, demographics, comorbidities, or ESRD aetiology. The VA type (PE vs. US): 47.6 vs. 69.2% radio-cephalic fistula* (*P<.05), 38.1 vs. 10.3% brachial-cephalic fistula*, 11.9 vs. 17.9% brachiobasilic fistula, and 2.4 vs. 2.6% humeral-axillary grafts. RCF patency rates: Immediate 90 vs. 85.2%, early 75 vs. 100%*, and late 88.9 vs. 55%*; respectively. However, an increase in AV performed in other territories was observed in PE group (25 vs. 3.7%*) in RCF. CONCLUSIONS: Routine doppler ultrasound mapping of upper extremities before VA creation in our centre allowed the distal vascular territory to be optimised, and improved the primary patency rates of both early and late radio-cephalic fistulas

Renal Arteriovenous Shunts: Clinical Features, Imaging Appearance, and Transcatheter Embolization Based on Angioarchitecture.

Renal arteriovenous (AV) shunt, a rare pathologic condition, is divided into two categories, traumatic and nontraumatic, and can cause massive hematuria, retroperitoneal hemorrhage, pain, and high-output heart failure. Although transcatheter embolization is a less-invasive and effective treatment option, it has a potential risk of complications, including renal infarction and pulmonary embolism, and a potential risk of recanalization. The successful embolization of renal AV shunt requires a complete occlusion of the shunted vessel while preventing the migration of embolic materials and preserving normal renal arterial branches, which depends on the selection of adequate techniques and embolic materials for individual cases, based on the etiology and imaging angioarchitecture of the renal AV shunts. A classification of AV malformations in the extremities and body trunk could precisely correspond with the angioarchitecture of the nontraumatic renal AV shunts. The selection of techniques and choice of adequate embolic materials such as coils, vascular plugs, and liquid materials are determined on the basis of cause (eg, traumatic vs nontraumatic), the classification, and some other aspects of the angioarchitecture of renal AV shunts, including the flow and size of the fistulas, multiplicity of the feeders, and endovascular accessibility to the target lesions. Computed tomographic angiography and selective digital subtraction angiography can provide precise information about the angioarchitecture of renal AV shunts before treatment. Color Doppler ultrasonography and time-resolved three-dimensional contrast-enhanced magnetic resonance angiography represent useful tools for screening and follow-up examinations of renal AV shunts after embolization. In this article, the classifications, imaging features, and an endovascular treatment strategy based on the angioarchitecture of renal AV shunts are described.

Diploic arteriovenous fistulas--classification and endovascular management.

BACKGROUND: The authors report on two cases of diploic arteriovenous fistulas (AVFs) in the left parieto-occipital region of a 20-year-old female and the right parietal region of a 68-year-old male. The clinical presentation, angiographic appearance, and endovascular management of these rare lesions are discussed. METHODS: Retrospective data from two patients with diplopic AVFs are examined with a review of all published cases of diploic arteriovenous fistulas. RESULTS: Where previously reported diploic AVFs showed venous drainage to be intracranial or combined, two case studies examined by the authors found exclusively extracranial drainage in the AVFs. In both case studies the lesions were primarily fed by the middle meningeal artery and treated via a transarterial endovascular approach using n-BCA glue. CONCLUSIONS: After reviewing all reported cases of AVF in the literature and combining our two new observations, we concluded that diploic AVFs can have three types of venous outflow: draining toward dural sinuses only, toward extracranial veins only, and combining the dural and extracranial pathways.

[Combined methods of treatment the congenital arterio-venous fistulas of peripheral vessels].

A 10-year experience and results of combined methods of surgical treatment of arterio-venous fistulas of peripheral vessels in 50 patients were analyzed. The patients were systematized on the basis of existing classifications, clinical manifestations of the disease, methods of invasive (ultrasound dopplerography and duplex scanning) and invasive (angiography) examinations. According to many authors no one of conventional methods of surgical treatment of arterio-venous fistulas which are used singly can be effective and must not be recommended as the most optimal. Stepwise employing of traditional operations and endovascular techniques are the main conditions for preventive measures of ischemic disorders in the limbs.

Right pulmonary artery to left atrial fistula: a description of two cases, emphasising a diagnostic approach.

Right pulmonary artery to left atrial fistula is a rare pathology characterised by a right to left shunt. Another important aspect of this pathology is the difficulty encountered in making a diagnosis, which is why the diagnosis is frequently delayed into adulthood. A description of two cases is used to emphasise the importance of the different modes of echocardiography as a diagnostic tool in diagnosis, as well as the two different clinical forms that it adopts: a group of patients suffering cardiac failure and cyanosis without apparent cause generally in neonates and a second group of mostly older patients with dyspnoea and cyanosis without apparent cause. Symptoms thus differ depending on the time of presentation and are related to the size of the fistula.

Classification schemes for arteriovenous malformations.

The wide variety of arteriovenous malformation (AVM) anatomy, size, location, and clinical presentation makes patient selection for surgery a difficult process. Neurosurgeons have identified key factors that determine the risks of surgery and then devised classification schemes that integrate these factors, predict surgical results, and help select patients for surgery. These classification schemes have value because they transform complex decisions into simpler algorithms. In this review, the important grading schemes that have contributed to management of patients with brain AVMs are described, and our current approach to patient selection is outlined.

Endovascular management of spinal vascular malformations.

Spinal vascular malformations are rare diseases with a wide variety of neurological presentations. In this article, arteriovenous malformations (both from the fistulous and glomerular type) and spinal dural arteriovenous fistulae are described and an overview about their imaging features on magnetic resonance imaging (MRI) and digital subtraction angiography is given. Clinical differential diagnoses, the neurological symptomatology and the potential therapeutic approaches of these diseases which vary depending on the underlying pathology are given. Although MRI constitutes the diagnostic modality of first choice in suspected spinal vascular malformation, a definite diagnosis of the disease and therefore the choice of suited therapeutic approach rests on selective spinal angiography. Treatment in symptomatic patients offers an improvement in the prognosis. In most spinal vascular malformations, the endovascular approach is the method of first choice; in selected cases, a combined or surgical therapy may be considered.

Preoperative evaluation of spinal vascular malformation by MR angiography: how reliable is the technique: case report and review of literature.

Contrast-enhanced MR angiography (MRA) has been increasingly used in the evaluation of spinal vascular malformations. Even though MR spinal angiography has several advantages over catheter spinal angiography (DSA), however, spinal DSA must never be omitted before operation, even if the vascular malformation is nicely demonstrated by MR angiography. We report a case of spinal vascular malformation in which MR angiography provided great images which almost convinced everyone about the type and site of malformation/fistula. The images were so convincing that it was almost decided to skip catheter based angiography, citing reason of disadvantages of catheter based angiography over MR angiography. However, spinal DSA was luckily done which completely changed the type and site of malformation and helped in avoiding failed surgery. We conclude that even though catheter based spinal angiography has disadvantages over MRA, it should never be omitted from the diagnostic protocol.