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PubMed2001

The importance of venous hypertension in the formation of dural arteriovenous fistulas: a case report of multiple fistulas remote from sinus thrombosis.

Various hypotheses have been reported concerning the pathogenesis of dural arteriovenous fistulas (DAVFs). However, it is still controversial whether sinus thrombosis or venous hypertension has a greater influence on the formation of DAVFs. We present a rare case of multiple DAVFs that developed after sinus thrombosis. Chronic venous hypertension secondary to sinus thrombosis in the left transverse-sigmoid sinus induced the multiple DAVFs, including one in the right cavernous sinus, which was remote from the occluded sinus. This case indicates the importance of venous hypertension in the formation of DAVFs.

Central Nervous System Vascular Malformations↗
PubMed2004

Immunohistochemical study in dural arteriovenous fistulas and possible role of local hypoxia for the de novo formation of dural arteriovenous fistulas.

OBJECTIVE: Although previous clinical and experimental studies investigated the pathogenesis of dural arteriovenous fistulas (DAVFs), the biological process leading to intracranial DAVFs so far remains unknown. In this study, we investigated the expression of vascular growth factors in order to elucidate the possible role of these factors in the development of DAVFs. METHODS: We examined the histological features, proliferative and angiogenic capacities of the tissue specimens obtained from eight patients who underwent surgery at our institution. Immunohistochemical staining for vascular endothelial growth factor (VEGF), its receptors Flk-1 and Flt-1, transforming growth factor alpha (TGFalpha), basic fibroblast growth factor (bFGF), hypoxia inducible factor 1alpha (Hif-1alpha), MIB-1 and proliferating cell nuclear antigen (PCNA) was performed using standard immunohistochemical techniques. RESULTS: A positive immunostaining was found for all antibodies studied except MIB-1, whereas nuclear endothelial expression of PCNA was observed in only 3/8 cases. Hif-1alpha and VEGF stained positive in all of the available specimens (7/7). Flk-1 showed a positive immunoreaction in only 2/8 cases and Flt-1 in 5/7 cases. TGFalpha and bFGF were expressed in the majority (6/8) of cases. CONCLUSION: These results indicate the possible role of local tissue hypoxia as the initial step causing neoangiogenesis and a low degree of endothelial proliferation in DAVFs. Such hypoxia might be caused by venous hypertension or venous thrombosis as it was previously suggested by other authors.

Adult↗
PubMed1998

Effects of ticlopidine in AV-fistula surgery in uremia. Fistula Study Group.

Two hundred and fifty-eight patients with uremia who were offered surgery for placement of an arteriovenous fistula for hemodialysis were recruited in nine regional dialysis centers. The patients were randomized to receive the platelet aggregation inhibitory compound ticlopidine, 250 mg b.d., or matching placebo. Study medication was targeted at 7, minimum 3, days before scheduled surgery and continued for 28 days after surgery. The overall rate of occlusion was 41/260 evaluable operations (16%), 25/131 (19%) in the placebo group and 16/129 (12%) in the ticlopidine group. The risk of early occlusion was a non-significant 35% lower in the ticlopidine group. Limited risk factor analysis did not clearly identify any subgroup other than females at greater risk of early thrombosis nor any subgroup deriving particular benefit from ticlopidine treatment.

Adult↗
PubMedDate not supplied

Resistive index measurement of native hemodialysis arteriovenous fistula feeding artery as a predictor for fistula dysfunction.

The aim of the present study was to evaluate resistive index (RI) in the feeding artery of the functioning and dysfunctioning arteriovenous fistulas (AVFs). Measurement of RI in the feeding artery using Doppler ultrasound was performed in 48 patients on hemodialysis. Twenty-seven upper arm AVFs and 21 radiocephalic AVFs were studied. The patients were categorized into three groups according to clinical function: group 1, AVFs with normal function (n = 21); group 2, AVFs with abnormal clinical function (reduced pump flow) (n = 20); and group 3, AVFs with abnormal clinical function (increased venous pressure) (n = 7). Resistive index measurements and morphologic changes were compared between functioning and dysfunctioning AVFs. Increased RI values were detected in the AVFs with reduced pump flow. The average RI values of feeding artery were 0.47 +/- 0.07 in group 1, 0.67 +/- 0.18 in group 2, and 0.49 +/- 0.05 in group 3. Two brachial artery aneurysms, one brachial artery pseudoaneurysm, ten venous stenoses, and six venous thromboses were detected in the AVFs with diminished pump flow (18/20 patients, 90%). Both increased RI values and vascular complications were detected by Doppler ultrasound in the patients with reduced pump flow during dialysis. This study shows that Doppler ultrasound examination of AVF feeding artery may provide useful data on morphologic and functional characteristics of AVF.

Adult↗
PubMed2006

Evaluation of primary failure in native AV-fistulae (early fistula failure).

The most preferable method of vascular access (VA) in maintenance hemodialysis is a native arteriovenous fistula (AVF). Advanced age as well as the rapid increase in underlying diseases such as diabetic nephropathy and nephrosclerosis in these patients also means that the veins and arteries used to establish the AVF have undergone vascular damage, making construction of an AVF more difficult compared with earlier construction. Although there are various conditions under which arterial superficialization or AV graft must be chosen, it remains the rule that the first choice for VA should be AVF whenever possible. To improve postoperative results, it is necessary to reduce malfunctions immediately following surgery. We conducted a survey of 23 dialysis facilities throughout Japan and analyzed data from the past 3 years regarding the functionality of the AVF at initial puncture following construction of 5007 examples of newly constructed AVFs. Upon initial puncture, primary failure (PF) is defined as those cases in which thrombosis or inadequate blood flow occur. Primary failure occurred in 7.6% of the cases in this series, but there was a wide distribution of PF, 0.8% to 23.6%, because of differences in quality among facilities. This difference in PF is probably affected by technical aspects, the main factor being the characteristics of the patient. Survey responses included: (1) vascular damage of the veins and arteries used in creating the AVF and (2) the suitability of the location chosen for construction. In the data collected, many methods were used to repair those primary AFVs in which PF occurred. The salvage rate was 70%. Currently, the most preferable form of VA is AVF adhering to the principle that the proper timing of the choice and construction of AVF should consider the maturation period. To accomplish this, it is vital that vascular mapping be performed preoperatively to construct the AVF. If PF does occur, the cause should be thoroughly investigated and repairs made effectively.

Arteriovenous Shunt, Surgical↗
PubMed2002

Dural arteriovenous fistulae developing at different locations after resolution of previous fistulae: report of three cases and review of the literature.

We present three cases of unusual dural arteriovenous fistulae developing at other dural sinuses after resolution of initial lesions by treatment. In all three cases, the second lesions developed at different sinuses ipsilateral to the initial lesions, and the intervals between the resolution of the initial lesions and the appearance of the second lesions was <12 months. Clinical characteristics, including those previously reported, are discussed.

Central Nervous System Vascular Malformations↗
PubMed2004

Immunohistochemical study in dural arteriovenous fistula and possible role of ephrin-B2 for development of dural arteriovenous fistula.

BACKGROUND: Although there were several clinical and experimental studies discussing the pathogenesis of dural arteriovenous fistula (DAVF), the pathological process leading to intracranial DAVF so far remains unknown. In this study, we investigated the expression of vascular growth factors in order to elucidate the possible role of these factors for the development of DAVF and to study the biological activity of this uncommon lesion. METHODS: We examined the histological features, proliferative and angiogenic capacities of the tissue specimens obtained from 6 patients who underwent surgery at our institution. Immunohistochemical staining for vascular endothelial growth factor (VEGF), its receptors Flk-1 and Flt-1, ephrin-B2, MIB-1 and proliferating cell nuclear antigen (PCNA) was performed using standard immunohistochemical techniques. RESULTS: A positive immunostaining was found for all antibodies studied except MIB-1, whereas nuclear endothelial expression of PCNA was observed in only 3/6 cases. VEGF stained positive in all of the available specimens (6/6). Flk-1 showed a positive immunoreaction in only 2/6 cases and Flt-1 in 4/6 cases. Ephrin-B2 was expressed in the majority (5/6) of the cases. CONCLUSIONS: These results support the hypothesis that DAVFs might be acquired dynamic vascular malformations with low biological activity. Vascular growth factors like VEGF and ephrin-B2 might play a pivotal role in the formation of DAVF.

Aged↗