Background: The most common form of vascular access for hemodialysis is a native arteriovenous fistula, which connects site of the artery to the end of the vein. The maturation process of the fistula plays a crucial role in the establishment of a functional vascular access. Radial artery stenosis is among others a potential cause of maturation failure. In these cases, improving the fistula's blood flow may be difficult, as traditional surgical reanastomosis and endovascular intervention frequently fail. Radial artery deviation and reimplantation (RADAR) is a novel, effective technique for creating primary fistulas with a high patency rate. The main disadvantage of this procedure is the ligation of the radial artery and the subsequent known consequences. Methods: In order to accelerate maturation, we used RADAR as a secondary fistula in three patients with radial artery stenosis and maturation failure. In all patients after surgery we observed significant increase in fistula blood flow. Two patients used fistula for hemodialysis after surgery. We describe the image diagnosis, procedure, and benefits of this method based on a single case. Conclusion: The RADAR technique may be successfully used as a secondary access in patients with maturation failure, due to RA stenosis to accelerate fistula maturation.

Patients with chronic renal failure and vascular diseases require the vascular access for hemodialysis procedure to be performed with the most possible comfort for the patient. Native vein graft has a longer-lasting term in the patients’ limb, lower risk of graft infection and lower price. Native vein graft is constructed from the great saphenous vein, if the diameter of the vessel is smaller than the diameters of vessels (brachial artery, cephalic vein) it is connected to in the cubital fossa region due to the risk of graft folding, that might occur, if the graft diameter is bigger than the diameter of one or both vessels, on which anastomosis is made. The most important sizes, that were taken before graft placement, are the length of the forearm compartment, the distance between the brachial artery and cephalic vein in the cubital fossa region, distance from an expected incision in the brachial artery to the middle of the forearm compartment, the distance between incision in cephalic vein to the middle of the forearm compartment, length of the great saphenous vein (the graft) and diameters of blood vessels, used in the procedure. Finally, the right position of the graft should be determined for the successful outcome of anastomosis creating procedure.

Hereditary Hemorrhagic Telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is a rare and inherited vascular disorder, characterized by the development of arteriovenous malformations (AVMs) in various organs and telangiectasia (small AVM) in the mucocutaneous. The majority of HHT patients have haploinsufficiency of genes involved in the transforming growth factor-beta (TGFβ) signaling pathway, including endoglin (ENG), activin receptor-like kinase 1 (ALK1, also known as ACVRL1), or SMAD4. Active angiogenesis is also required for telangiectasia and AVM development. Anti-angiogenic strategies have been tested in patients and animal models extensively. However, the exact mechanisms for telangiectasia and AVM development remain unclear. In this review, we discuss recent advances in identifying disease mechanisms, and potential therapeutic targets.

Hemorrhagic complications arising from ventricular drainage procedures are typically asymptomatic and of low volume. A particular subset of these complications known as Delayed Intracranial Hemorrhage (DICH) is however recognized for its particularly poor prognosis. We primarily aimed to identify epidemiological characteristics associated with DICH, to shed light on its occurrence and potential risk factors. To do so, we performed a retrospective analysis of a series of ten patients who presented with DICH in the context of a ruptured brain Arteriovenous Malformation (bAVM), and a systematic literature review of all DICH cases reported in the literature. Our ten patients showed delayed neurological deterioration after Ventriculoperitoneal Shunt (VPS) procedure, with a computed tomography (CT) scan revealing a DICH surrounding the ventricular catheter, distinct and away from the nidus of their previously ruptured bAVM. Four patients (40%) rapidly declined and passed away, three (30%) required surgical management and the remaining three (30%) demonstrated gradual clinical improvement with conservative management. In the literature, most patients presenting with DICH had hydrocephalus associated with neurovascular disorders (47% of cases), such as bAVM rupture in our present series. These constatations point out the significance of underlying pathologies potentially predisposing to these unusual complications.

Pulmonary arteriovenous malformation (PAVMs) in children are rare lesions characterized by abnormal low resistance vascular structures connecting a pulmonary artery to a pulmonary vein, resulting in an intrapulmonary right-to-left shunt. The insidious onset and variable signs and symptoms make diagnosis difficult, especially in children. PAVMs  can be single or multiple, congenital or acquired, and up to 47-80% of cases are associated with hereditary hemorrhagic telangiectasia (HHT).We present the  case of a 12-year-old female teenager referred to our center for epistaxis, headache, fatigue and weakness, with evidence of mild oxygen desaturation.  Bubble test showed a right-to-left shunt and pulmonary angio-CT confirmed the diagnosis. Percutaneous selective embolization was performed with full recovery of normal arterial oxygen saturation. When differentiating between mild oxygen desaturation and exercise intolerance in children and adolescents, physicians should be aware of the possibility of PAVMs as a cause. 

Preoperative angiography in glioblastoma (GBM) often shows arteriovenous shunts and early venous filling (EVF). Here, we investigated the clinical implications of EVF in GBM as a prognostic and vascular mimicry biomarker. In this retrospective multicenter study, we consecutively enrolled patients who underwent angiography with a GBM diagnosis between April 1, 2013, and March 31, 2021. The primary and secondary endpoints were the differences in overall survival (OS) and progression-free survival (PFS), respectively, between cases with and without EVF. Of 133 initially enrolled patients, 91 newly diagnosed with GBM underwent preoperative angi-ography and became the study population. The 6-year OS and PFS were significantly worse in the EVF than in the non-EVF group. Moreover, 20 GBM cases (10 with EVF and 10 without EVF) were randomly selected and evaluated for histological vascular mimicry. Except for two cases that were difficult to evaluate, the EVF group had a significantly higher frequency of vascular mimicry than the non-EVF group (0/8 vs. 5/10, P = 0.04). EVF on preoperative angiography is a robust prognostic biomarker for GBM and may help detect cases with a high frequency of histological vascular mimicry.

Introduction: Capillary malformation-arteriovenous malformation (CM-AVM; MIM#608354) is caused by germline RASA1 and EPHB4 alterations. RASA1 intralesional second hits have also been reported. Constitutional mosaicism, defined as the presence of a mosaic variant in all cell types of an individual, is detected in clinical practice as mosaic variants in multiple tested samples from one individual or as mosaic variants in blood samples in a disorder affecting another cell/tissue types. Here we report RASA1 constitutional mosaicism in CM-AVM. Subjects and methods: A custom high-throughput sequencing panel was used to search for RASA1 pathogenic variants in blood samples from two unrelated patients with a clinical diagnosis of CM-AVM. An affected tissue sample from one of the patients was also analyzed. Results: Both patients showed different nonsense RASA1 variants in mosaic in blood samples and in the corresponding affected tissue sample from one of the patients. The mosaicism ranged between 7% and 21,5%. Conclusions: We report for the first time the presence of RASA1 constitutional mosaicism in CM-AVM. Constitutional mosaicism has implications for accurate molecular diagnosis and recurrence risk, and helps to explain the great phenotypic variability in CM-AVM.

Brain arteriovenous malformations (BAVMs) are a critical concern in hereditary hemorrhagic telangiectasia (HHT) patients, carrying the risk of life-threatening intracranial hemorrhage. While traditionally seen as congenital, the debate continues due to documented de novo cases. Our primary goal was to identify the precise postnatal window in which deletion of the HHT gene Endoglin (Eng) triggers BAVM development. We employed SclCreER(+);Eng2f/2f mice, enabling timed Eng gene deletion in endothelial cells via tamoxifen. Tamoxifen was given at four postnatal periods: P1-3, P8-10, P15-17, and P22-24. BAVM development was assessed at 2-3 months using latex dye perfusion. We examined angiogenic activity by assessing vascular endothelial growth factor receptor 2 (VEGFR2) expression via Western blotting and Flk1-LacZ reporter mice. Longitudinal magnetic resonance angiography (MRA) was conducted up to 9 months. BAVMs emerged in 88% (P1-3), 86% (P8-10), and 55% (P15-17) of cases, with varying localization. Notably, the P22-24 group did not develop BAVMs but exhibited skin AVMs. VEGFR2 expression peaked in the initial 2 postnatal weeks, coinciding with BAVM onset. These findings support the “second hit” theory, highlighting the role of early postnatal angiogenesis, in initiating BAVM development in HHT type I mice.

In this study, we developed a model that can predict whether patients with cerebral arteriovenous malformation (AVM) will be cured 36 months after intervention by means of stereotactic radiosurgery (SRS), and identified the most important predictors that explain the probability of being cured. A machine learning (ML) approach was applied using decision tree (DT) and logistic regression (LR) techniques on historical data (sociodemographic, clinical, treatment, angioarchitecture, and radiosurgery procedure) of 202 patients with AVM who underwent SRS at the Instituto de Radiocirugía del Perú (IRP) between 2005 and 2018. The LR model obtained the best results for predicting AVM cure with an accuracy of 92.16%, sensitivity of 92.86%, specificity of 88.89%, precision of 97.50%, and AUC of 97.62%, which shows that ML models are suitable for use for predicting the prognosis of medical conditions such as AVM and can be a support tool for medical decision-making. In addition, several factors were identified that could explain whether patients with AMV would be cured at 36 months with the highest likelihood: the location of the AVM, the occupation of the patient, and the presence of hemorrhage.

Increased soluble endoglin (sENG) were observed in human brain arteriovenous malformations (bAVMs), and overexpression of sENG with vascular endothelial growth factor (VEGF)-A induced dysplastic vessel formation in mouse brain. However, the underlying mechanism of sENG-induced vascular malformations is not clear. While evidence suggests the role of sENG as a pro-inflammatory modulator, increased microglial accumulation and inflammations were observed in bAVMs. Therefore, we hypothesized that microglia mediate sENG-induced inflammation and endothelial cell (EC) dysfunction in bAVMs. In this study, we confirmed that sENG with VEGF-A overexpression induced dysplastic vessel formation. Remarkably, there were increased microglial activation around dysplastic vessels with expression of NLRP3, inflammasome marker. We found that sENG increased the gene expression of VEGF-A, pro-inflammatory cytokines/inflammasome mediators (TNF-α, IL-6, NLRP3, ASC, Caspase-1, and IL-1β), and proteolytic enzyme (MMP-9) in BV2 microglia. The conditioned media from sENG-treated BV2 (BV2-sENG-CM) significantly increased angiogenic factors (Notch-1 and TGFβ) and pERK1/2 in ECs while it decreased IL-17RD, an anti-angiogenic mediator. Finally, the BV2-sENG-CM significantly increased EC migration and tube formation. Together, our study demonstrates that sENG provokes microglia to release angiogenic/inflammatory responses which may be involved in EC dysfunction. Our study suggests the contribution of microglia in the pathology of sENG-associated vascular malformations.

Background: Increase of collagen I (COL I)/COL III ratio enhances vessel wall stiffness and renders vessels less resistant to blood flow and pressure changes. We hypothesized that COL I/COL III ratio is increased in the brain arteriovenous malformations (bAVMs), which is associated with bAVM hemorrhage. Method: Surgically resected human bAVM samples and mouse bAVMs induced in three transgenic mouse lines with activin receptor-like kinase 1 or endoglin deletion in the endothelial cells or in the brain focally. Colony-stimulating factor receptor inhibitor was used to transiently deplete microglia. COL I and COL III levels, hemorrhage, and gene expression in bAVMs were analyzed. Results: The COL I and COL III levels and the COL I/COL III ratio were higher on human and mouse bAVMs than controls, which was associated with bAVM hemorrhage. Col I and Col III mRNAs were also increased in mouse bAVMs. The degree of microhemorrhage in mouse bAVMs was positively correlated with Col I/Col III ratios. Transient depletion of microglia reduced Col I/Col III ratio and microhemorrhage in mouse bAVMs. Conclusion: COL I/COL III ratio are increased in bAVM vessels, which is associated with bAVM hemorrhage. Depletion of microglia reduces Col I/Col III ratio and hemorrhage in mice bAVMs.

Background: The purpose was to develop a novel hypothetical method to increase the size of coronary arteries. Methods: In the long-term observation the coronary sizes were dilated in three unexpected scenarios. The coronary artery sizes were observed in patients with mitral stenosis (n=59) by angiogram prior to percutaneous balloon mitral valvuloplasty or valve replacement surgery for severe mitral stenosis. The coronaries of patients with patent ductus arteriosus who underwent surgical closure in the past (n=12) were examined by echocardiogram. Patients with renal failure on long-term dialysis through peripheral arterio-venous fistula without left ventricular hypertrophy (n=17) were studied by echocardiography. Normal age, weight and sex matched coronary sizes served as controls in the study. All these observations were made over a period of 11.5 years. Results: The sizes of coronaries in patients with mitral stenosis, patients who underwent closure for patent ductus arteriosus, and in patients on hemodialysis through arteriovenous fistulas were higher than normal controls (p<0.05, for all). A hypothetical model to increase the coronary sizes could be developed based on the analysis of the differential equations of Poiseuille’s. The proposed method is creating a peripheral arterio-venous fistula, which could be closed later electively by a percutaneous method/surgery. The closure time needs to be determined by experimental studies. The other methods could be a continuous exercise program or usage of beta-blockers. Conclusion: A novel hypothetical method of peripheral arteriovenous fistula formation could potentially increase the size of the coronaries, and this could be closed later.