Abstract 1122‐000061: Initial Experience Using the Transvenous Embolization for Intracranial Arteriovenous Malformations in a Reference Endovascular Center
Authors: Zapata Giancarlo Saal , Saal‐Zapata Giancarlo , Rodriguez‐Calienes Aaron , Rodriguez‐Varela Rodolfo 
Published: December 2021

Introduction
: Transvenous embolization (TVE) is used in cases of arteriovenous malformations (AVMs) with specific characteristics such as small size (<3 cm), deep location, single draining vein and the absence of adequate feeders. High complete obliteration rates have been reported. Therefore, our study aimed to analyze our initial experience using the TVE for treatment of AVMs.

Methods
: Between May 2018 and January 2021, consecutive patients who underwent TVE of AVMs were selected. Demographics, radiological and clinical variables were collected. The modified Rankin Scale (mRS) was used to determine clinical outcomes and was dichotomized (good clinical condition: mRS £2; poor clinical condition: mRS >2). Complete obliteration was defined as the total absence of the nidus and vein, subtotal obliteration was defined as the embolization of >95% of nidus and partial obliteration was defined as the embolization of <95% of nidus. Procedure‐related complications were defined as those that occurred during the procedure and were divided as intraoperative rupture and thrombosis.

Results
: Twenty‐one patients harboring 21 AVMs were evaluated. Fourteen patients (67%) were women. The mean age was 24.5 ± 14.1 years (7 – 48 years). A good preoperative clinical condition was present in 20 patients. Twenty AVMs were ruptured (95.2%). The most frequent locations were thalamus/basal ganglia in 6 patients (29%), followed by temporal/insular in 5 patients (24%). Spetzler‐Martin grades III, II and I were present in 11, 9 and 1 patients, respectively. The mean number of feeders was 2.1 per AVM. The feeders arised from the MCA in 9 cases, followed by PCA in 5 cases, ACA and AChoA in 3 cases, AICA in 2 cases, and ECA and PCom in 1 case, respectively. The mean number of veins was 1.3 per AVM. Deep venous drainage was present in 12 cases (57%). The mean size of the AVM nidus was 15.7 ± 7.8 mm (3.7 – 34 mm). Previous trans‐arterial embolization was done in 10 patients (47.6%). Pre‐embolization hematoma evacuation was done in 4 patients (19%). An immediate complete obliteration was achieved in 18 patients (85.7%), whereas a subtotal and partial obliteration were achieved in 2 and 1 patients, respectively. A poor post‐operative clinical condition occurred in 4 patients (20%). Procedure‐related complications occurred in 4 patients (20%): 3 cases with intra‐operative rupture of the AVM nidus and 1 case of a thrombus in the M1 treated with stent retriever. Mortality occurred in 3 patients (14.2%) of which two presented intra‐operative rupture with intracerebral hematomas that required decompressive craniectomy. One patient presented a post‐operative bleeding of the AVM nidus that required external ventricular drainage and decompressive craniectomy. Follow‐up angiography was done in 4 cases with total obliteration of all the cases (100%).

Conclusions
: The transvenous approach has emerged as an alternative to trans‐arterial approach with high grades of immediate total obliteration rates, but with potential procedure‐related complications. Thus, this technique should be used in selected cases in order to achieve complete cure rates.