Embolização percutânea de fístulas arteriovenosas pulmonares / Percutaneous embolization of pulmonary arteriovenous fistulas

Malformações arteriovenosas pulmonares são uma comunicação anormal entre uma artéria e uma veia, causando manifestações clínicas, como hipoxemia crônica e eventos embólicos. As malformações arteriovenosas eram tratadas cirurgicamente, com taxa expressiva de complicações. Na década de 1970, a primeira embolização percutânea por cateter foi realizada com molas. Descrevemos três casos nos quais técnicas de embolização percutânea foram efetivas em prevenir eventos embólicos, hemorrágicos e hipoxêmicos no seguimento dos pacientes.

Pulmonary arteriovenous malformation is an abnormal communication between an artery and a vein, causing clinical manifestations, such as chronic hypoxemia and embolic events. Arteriovenous malformations were treated surgically, with a significant rate of complications. In the 1970 ́s, the first percutaneous catheter embolization was performed with coils. We describe three cases in which percutaneous embolization techniques were effective to prevent embolic, hemorrhagic, and hypoxemic events in the follow-up of patients.

Surgical Treatment for Occlusion of Graft Arteriovenous Fistula in Patients Undergoing Hemodialysis

BACKGROUND: Maintenance of adequate vascular access for hemodialysis is important in patients with end-stage renal disease. Once arteriovenous fistula (AVF) occlusion occurs, the patient should be treated with rescue therapy. This study was performed to evaluate the results of a rescue therapy for AVF occlusion. METHODS: From January 2008 to December 2012, 47 patients who underwent surgical rescue therapy for AVF occlusion after graft AVF formation, were enrolled in this study. The patients were divided into two groups, namely the graft repair group (group A, n=19) and the thrombectomy group (group B, n=28). Postoperative results of both groups were analyzed retrospectively. RESULTS: There were no statistically significant differences in the clinical characteristics between the two groups. In terms of the duration of AVF patency after the first rescue therapy, group A showed a longer AVF patency duration than group B (24.5+/-21.9 months versus 17.7+/-13.6 months), but there was no statistically significant difference (p=0.310). In terms of the annual frequency of AVF occlusion after the rescue therapy of group A was lower than that of group B (0.59 versus 0.71), but there was no statistically significant difference (p=0.540). The AVF patency rates at 1, 2, 3, and 5 years after the first rescue therapy in group A were 52.6%, 31.5%, 21.0%, and 15.7%, respectively, and those in group B, they were 32.1%, 25.0%, 17.8%, and 7.14%, respectively. There was no statistically significant difference (p=0.402). CONCLUSION: Graft repair revealed comparable results. Although there was no statistically significant difference, the patent duration and annual frequency of AVF occlusion of group A were better than those of group B. Therefore, graft repair is considered as a safe and useful procedure for maintaining graft AVF.

Diagnosis of Arteriovenous Fistulas following a Lumbar Discectomy

PURPOSE: To evaluate the relevant clinical and radiographical findings for the diagnosis of an arteriovenous fistula after a lumbar discectomy. MATERIALS AND METHODS: Five patients with an arteriovenous fistula following a lumbar discectomy were preoperatively diagnosed and treated. We retrospectively evaluated the level of surgery, injured vessels, clinical symptoms, physical findings, and the interval between surgery and treatment. Effective and fast diagnostic methods for determining the presence of a postoperative arteriovenous fistula were evaluated. RESULTS: All of the arteriovenous fistulas resulted from operative injuries of the iliac arteries and veins. They were diagnosed after a mean time of 22 months (range 2 months-4 years) in spite of various symptoms and signs shortly after surgery. The arteriovenous fistulas were confirmed with angiography and were treated by surgery for 3 patients and by insertion of a stent-graft in 2 patients. Postoperative CT angiography showed the complete occlusion of the fistula tract and the normal blood flow. CONCLUSION: Essential clinical information and radiological examination, especially CT angiography with 3D reconstruction, is necessary to obtain to diagnose an arteriovenous fistula after a lumbar discectomy.

Efficacy of Preoperative US Vascular Mapping for Arteriovenous Fistula in Patients with Hemodialysis

PURPOSE: The purpose of this study is to assess the efficacy of preoperative US vascular mapping to predict postoperative patency of the arteriovenous fistula for hemodialysis. MATERIALS AND METHODS: Sixty-six patients who underwent hemodialysis for end-stage renal failure (M: F=34:32, mean age, 58.8 years) were observed prospectively from January 2001 to April 2003. The patients were divided into two groups: the vascular mapping group and the control group. A comparative analysis of the re-operation rate between the two groups was determined by use of the chi-square rest, efficacy of preoperative US vascular mapping according to the type of surgery. A comparative analysis of the secondary patency after percutaneous transluminal angioplasty was determined by the use of Fischer exact test, and a comparative analysis of the diminution of patency during the follow-up periods was determined by the use of the Log-rank test. In the mapping group, the diameters of intraoperatively selected vessels were investigated and compared with the recommended diameter on preoperative US vascular mapping determined statistically by the use of Fisher's exact test. RESULTS: The preoperative US vascular mapping group had relatively lower re-operation rates (11.8%) than the control group (28.1%) (p=0.09). The preventive role of US vascular mapping is more effective in decreasing the re-operation rate for a native arteriorvenous fistula (7.4%) than for a synthetic arteriovenous graft (25.9%) (p=0.06). For patients that had an interventional procedure, the failure rate to obtain a secondary patency was smaller than in the mapping group (33.3%), compared with the control group (46.3%) (p=0.37). Patients in the mapping group had a higher patency than the control group patients for a native arteriovenous fistula (92.0%) and a synthetic arteriovenous graft (71.4%) at one year following surgery (p=0.10, p=0.79). The arteriovenous fistulas in the mapping group had a higher patency for both a native arteriovenous fistula (16.6%) and a synthetic arteriovenous graft (22.2%), which was statistically significant (p=0.01, p=0.03). CONCLUSION: Preoperative US vascular mapping is considered to be a useful technique for the preoperative evaluation of an arteriovenous fistula and to contribute to maintaining its postoperative patency and reducing the rate of repeated surgery.

Endovascular Treatment of Traumatic Carotid- Jugular Fistula: Report of Two Cases

We report 2 patients with a traumatic carotid- jugular fistula. The first patient suffered a deep neck penetrating injury. The external carotid-jugular fistula was demonstrated by 3-dimension CT angiography (3D CTA) and digital subtraction angiography (DSA). The patient was treated with coil embolization. The second patient suffered a gun shot injury to the neck. 3D CTA and DSA revealed a common carotid-jugular fistula and a pseudoaneurysm. The common carotid-jugular fistula was treated with coil embolization in the fistula and the pseudoaneurysm was treated with stent assisted coil embolization.

Percutaneous Treatment of Failed Native Dialysis Fistulas: Use of Pulse-Spray Pharmacomechanical Thrombolysis as the Primary Mode of Therapy

OBJECTIVE: To determine the efficacy and outcome of percutaneous treatment in restoring the function of failed native arteriovenous fistulas (AVFs) where pulse-spray pharmacomechanical thrombolysis was used as the primary mode of therapy. MATERIALS AND METHODS: From June 2001 to July 2005, 14 patients who had thrombosis of native AVFs underwent percutaneous restoration following 20 episodes of thrombosis. These included 6 repeated episodes in one forearm AVF and two episodes in another forearm AVF. All patients except one were treated with urokinase injection utilizing the pulse-spray technique and had subsequent balloon angioplasty. One patient was treated by percutaneous angioplasty alone. We retrospectively evaluated the feasibility of percutaneous treatment in restoring the function of the failed AVFs. The primary and secondary patencies were calculated by using a Kaplan-Meier analysis. RESULTS: Both technical and clinical success were achieved in 15 (75%) of 20 AVFs. Four of the five technical failures resulted from a failure to cross the occluded segment. One patient refused further participation in the trial through a brachial artery access following failure to cross the occluded segment via an initial retrograde venous puncture. There were no major precedure related complications observed. Including the initial technical failures, primary patency rates at six and 12 months were 64% and 55%, respectively. Secondary patency rates at six and 12 months were 71% and 63%, respectively. CONCLUSION: Pulse-spray pharmacomechanical thrombolysis for treatment of the thrombosed AVFs is safe, effective and durable. This procedure should be considered as an option for the management of failed AVFs prior to surgical intervention.

Transvenous Embolization in Patients with Dural Arteriovenous Fistula

PURPOSE: To evaluate the efficacy of transvenous embolization in patients with dural arteriovenous fistula (DAVF). MATERIALS AND METHODS: From October 2002 to July 2004, eight patients with angiographically confirmed DAVF underwent transvenous embolization of the affected dural sinuses. Concomitant transarterial embolization was performed in four patients. Patients included five men and three women aged 45-78 years (mean age, 55.4 years). The patient's medical records and angiographic features were retrospectively reviewed. Patients had follow-up periods ranging from 5 to 24 months (mean, 16.5 months). RESULTS: The locations of DAVF were transverse - sigmoid sinus in six patients and cavernous sinus in two patients. According to Cognard's classification, four of the DAVFs were Type I, two were type IIa, and two were Type IIb. Embolic materials used for the transvenous embolization were platinum detachable coils and fibered microcoils. After the transvenous embolization, there was complete obliteration of the DAVF in seven patients and significant flow reduction in one patient. All cases were clinically successful. There were no transient or permanent complications as a result of the endovascular procedures in any of the patients. One patient who had symptom recurrence 2 months after the initial treatment was successfully treated with repeated transvenous embolization. The remaining seven patients had no symptom recurrence during the follow-up period. CONCLUSION: Transvenous embolization is an effective and safe method in the treatment of patients with DAVF.

Efficacy of Percutaneous Transluminal Angioplasty for Treating Non-Maturing Brescia-Cimino Fistulas

PURPOSE: We wished to report our experiences for the treatment of non-maturing Brescia-Cimino fistulas by using percutaneous transluminal angioplasty (PTA). MATERIALS AND METHODS: From January 1997 and December 2003, we treated 22 patients with non-maturing Brescia-Cimino fistulas by using percutaneous transluminal angioplasty (PTA). A retrospective analysis was performed on the findings of the fistulograms, techniques and success rate of the PTA, and the patency rate. RESULTS: Seventeen segmental stenoses and 5 segmental occlusions of the cephalic veins were identified. Sixteen stenoses and 2 occlusions were located at the cephalic vein adjacent to the anastomosis site, and 3 occlusions and 1 stenosis are seen at the proximal vein near the elbow joint. In addition to venous stenosis, a focal arterial stenosis at the anastomosis site and two accompanying accessory veins that might hamper the maturation of main cephalic vein was seen in each of two patients, respectively, and the simultaneous occlusion of the left innominate vein as well as occlusion of the cephalic vein was noted in one patient. The initial success rate of the PTA procedures was 95.5% (21/22). The overall success rate including the 11 additional PTAs that were performed during follow-up was 96.9% (32/33). No major complication were noted to have occurred. The primary and secondary patency rates were 72% (16/22) and 95% (21/22) at 3 months, and 50% (11/22) and 77% (17/22) at 6 months, respectively. CONCLUSION: PTA is an effective and safe method for treating non-maturing Brescia-Cimino fistulas.

Contrast-Enhanced MR Angiography of Failing Hemodialysis Arteriovenous Fistulas and Grafts: A Preliminary Experience

PURPOSE: The purpose of this report is to evaluate the vascular stenosis for failing hemodialysis arteriovenous fistulas and grafts using contrast-enhanced MR imaging (CE-MRI) and to compare the results with digital subtraction angiography (DSA). MATERIALS AND METHODS: Nine patients (27 segmental vessels) with symptoms and signs of AVF stenosis or occlusion who presented to our medical department were recruited into this prospective comparative study. All of the patients with Brescia-Cimino arteriovenous fistula (AVF) or synthetic polytetrafluoroethylene (PTFE, Goretex(R)) loop graft underwent MRA and DSA of the fistula. MRA was performed with a 1.5-T system using VIBE sequence: TR/TE=3.5/1.5 msec, flip angle 20-25degrees, matrix 115x256, FOV 350x350, interpolated slice thickness 2.0 mm, fat suppression, scan time 13-18 sec and total time of 5 min. DSA was used as the reference standard for assessing the accuracy of MRA, and MRA was analyzed for the presence of stenosis or occlusion, a grading of stenosis, and the presence of collateral vessels. Two radiologists prospectively analyzed the MRAs by working in consensus. RESULTS: Regarding the stenotic grade, CE-MRA corresponded with the DSA in six patients (66.7%) and it overestimated the stenoses in three patients (33.3%). For the stenotic site, MRA had a sensitivity of 86.4%, a specificity of 40%, a positive predictive value of 32.1%, and a negative predictive value of 66.7%. CONCLUSION:Multiphase CE-MRA of the AVF noninvasively provided information comparable to that provided by DSA for the vascular stenosis regarding failing hemodialysis arteriovenous fistula.

Percutaneous Intervention for Permanent Hemodialysis Access

PURPOSE: To evaluate the effectiveness of percutaneous transluminal angioplasty (PTA) and pulse-spray pharmacomechanical thrombolysis (PSPMT) using urokinase for the management of insufficient hemodyalitic access, and to identify contributory patency-related factors following interventional procedures. MATERIALS AND METHODS: Between August 1995 and July 2001, 105 cases of insufficient hemodyalitic access involving 38 artificial arteriovenous fistulae (AVF) and 67 graft arteriovenous fistulae (AVG) were treated interventionally. The patients underwent PTA alone in 53 cases and PSPMT combined with PTA in 47, and procedural success and long-term patency were evaluated in terms of a patient's age and sex, the presence of diabetes, the location of access, the type of AVG, the draining vein of AVG, the presence of central vein stenosis, the degree of residual stenosis, and the method of interventional procedure, and contributory factors were thus identified. RESULTS: The overall technical success rate of interventional management was 83.8% (88/105), while the overall primary patency rate was 58.7+/-5.2% at 6 months, 43.0+/-6.0% at 1 year, and 18.1+/-6.0% at 2 years. In AVF/AVG groups, primary patency rates were 55.9+/-9.2%/57.8+/-6.5% at 6 months, 45.8+/-10.0%/42.7+/-8.4% at 1 year, and 21.8%+/-9.8%/18.9+/-6.5% at 2 years. The overall secondary patency rate was 40.0+/-8.1% at 2 years. No contributory factors were found (95% confidence level), though patency of access decreased when residual stenosis was more than 30% (p=0.054). CONCLUSION: Interventional management of insufficient hemodyalitic access has high success and patency rates, and is an effective primary method. There appear to be no contributory factors, though residual stenosis of more than 30% tends to decrease the patency of hemodialytic access.

Percutaneous Intervention in the Management of Insufficient Native Arteriovenous Hemodialysis Fistulae

PURPOSE: To determine the effectiveness and patency of percutaneous intervention in insufficient native arteriovenous hemodialysis fistulae (AVFs). MATERIALS AND METHODS: Between March 1997 and September 2001, 67 cases of insufficient native AVF in 56 patients were treated by endovascular intervention. Except eight cases of insufficient native AVFs resulted from central vein lesion, PTA was performed in 48 cases, and thrombolytic therapy with or without PTA in 11. In eight of the cases, in which central vein stenosis had led to the insufficency, percutaneous transluminal angioplasty (PTA) was performed, and in three of the eight, a stent was inserted. Angiographic findings and complications, as well as success and patency rates in the non-thromobosis and thrombosis group, were evaluated; the central vein lesion group was analysed separately. RESULTS: Among 84 lesions observed at angiography, there were 54 cases of stenosis, 17 of occlusion, and 13 of combined thrombosis. The lesions were located in a proximal vein (n=51), distal vein (n=14), artery (n=6), and at the site of anastomosis (n=13). In the central vein lesion group (n=8), seven cases of stenosis and one of occlusion were noted. The overall procedural success rate was 79.1% (53/67). That is, in patients with no central vein lesion, the procedural success rate of PTA of native AVFs was 85.4% (41/48) and the patency rates of this were 83.1% at 6 months and 67.4% at 12 months. In cases of thrombolysis with/without PTA, the procedural success rate was 54.5% (6/11) and the patency rates were 83.3% at 6 months and 62.5% at 12 months. Finally, in patients with a central vein lesion, the procedural success rate was 75% (6/8) and the patency rates were 80% at 6 months and 30% at 12 months. There was one case of pseudoaneurysm formation at the puncture site of the brachial artery, which was used as the access route for intervention; one embolism in the brachial artery; and three cases of vascular spasm and two of hematoma which did not require active treatment. CONCLUSION: Percutaneous intervention offers effective and safe management of insufficient AVFs. The procedural success rate was higher for stenosis than for thrombotic occlusion.

Effect of Percutaneous Transluminal Angioplasty in insufficiency of Arteriovenous Fistula for Hemodialysis

PURPOSE: To evaluate the effectiveness of percutaneous transluminal angioplasty(PTA) and to determine thefactors affecting the long-term patency rate in the management of insufficient hemodialytic arteriovenousfistula(AVF). MATERIALS AND METHODS: Forty-nine cases of insufficient hemodialytic AVF were treated in 44patients(native AVF:20, graft AVF:29, M:17, F:27, Age:22-70 years). In 28 thrombus patients, thrombolysis wasperformed with urokinase, and was followed by PTA. The initial success rate and complications of PTA wereevaluated. According to the site and length of the stenosis, type and age of the AVF, the presence or abscence of thrombus, a history of diabetic mellitus, the patient 's age, and the duration of renal failure, patency rateswere compared within each subgroup using the Kaplan-Meier logrank test. RESULTS: The initial success rate of PTAfor insufficient hemodialytic AVF was 88%(43/49), the patency rate of PTA was 67% at 6 months, and 50% at 12months. The initial success rate of thrombolysis was 89%(25/28). The complication rate of PTA was 12%(6/49), ofwhich five cases were vein rupture, and one was subcutaneous hematoma. Statistically, the patency rates in theabove mentioned subgroups were not significantly different. CONCLUSION: PTA with or without thrombolysis offerssafe and effective management of insufficient hemodialytic AVF.

MR Findings of Dural Arteriovenous Fistula in Cavernous Sinus

PURPOSE: To evaluate the MR findings of dural arteriovenous fistula(DAVF) in the cavernous sinus and to determine the most useful imaging method for the diagnosis of DAVF. MATERIALS AND METHODS: We evaluated the MR findings of 12 patients in whom DAVF was diagnosed in the cavernous sinus on the basis of angiographic findings. Axial T1- and T2-weighted, and axial and coronal Gd-enhanced T1-weighted images with 3-6mm slice thickness had been obtained, and the findings of DAVF on three pulse sequences were examined and compared. On the basis of the detection of DAVF on three pulse sequences, the MR findings were graded as excellent, fair or poor, and the location of DAVF in the cavernous sinus was analysed. We also classified DAVFs as group A or B on the basis of MR findings (group A: lesions in the cavernous sinus were as large as or larger than the cavernous internal carotid artery; group B: these were smaller than the cavernous internal carotid artery) and compared with cognard type on angiogram. RESULTS: Multiple tortuous signal voids were found in all DAVFs. The signal voids were located mainly in the middle and posterior one third of the cavernous sinus, as seen on axial images, and the middle and inferior one third, as seen on coronal images. Axial and coronal enhanced T1-weighted images showed an excellent grade in 11 of 12 cases and a fair grade in 1 of 12. Axial T2-weighted images showed an excellent grade in 6 of 12 cases and a fair grade in 4 of 12. T1-weighted images showed an excellent grade in 4 of 12 cases and a fair grade in 6 of 12. Six cases were group A, and 5 of the 6 were Cognard type IIa or IIb; The other 6 cases were group B, 5 of the 6 were Cognard type I. CONCLUSION: MR findings of multiple tortuous signal voids in the cavernous sinus, especially in the posterior or inferior portion, suggest DAVF, and enhanced T1-weighted imaging could be the most useful sequence for its diagnosis.

The Results of Embolization of Dural Arteriovenous Fistula

PURPOSE: To assess the embolization effect of dural arteriovenous fistula(DAVF). MATERIALS AND METHODS: Weevaluated 23 patients with DAVF who were diagnosed using digital subtraction angiography and treated bytransarterial and/or transvenous emobolization. The locations of DAVFs, as seen on angiography were as follows: 16in the cavernous sinus, four in the major dural sinuses, two in the jugular bulb, one in the torcula Herophili,and one in the tentorium cerebelli. On the basis of venous drainage patterns, Cognard's classification of DAVF wasused. Among our 23 patients, 13 underwent transarterial embolization, six underwent transvenous embolization, andfour underwent both. After embolization, three patients underwent other treatment: surgery, one ; gammairradiation, one ; and both. One. Polyvinyl alcohol particles or glue was used in transarterial embolization, andtungsten, platinum, or Guglielmi detachable coils in transvenous embolization. To analyse the residual lesion inDAF, we compared pre- and post-treatment angiograms ; patients were followed up for 2 to 48 months, and theircondition was assessed as cured, improved, not changed, or aggravated. RESULTS: Nine patients were found to beCognard type I, two were IIa, four were IIa+b, and eight were type III. Of our 23 patients, 12 were cured, tenimproved, and one was aggravated ; of the 13 who underwent transarterial embolization, four were cured, eightimproved, and one was aggravated ; of the six who underwent transvenous embolization, five were cured and oneimproved. The condition of a patient with a lesion in the torcular herophili was aggravated despite surgery andgamma irradiation after embolization. CONCLUSION: DAVF can be managed successfully with endovascular treatment.The outcome of the transvenous approach appears to be better than that of the transarterial approach alone. In acase involving a lesion in the torcular herophili, the outcome was poor and more aggressive treatment wasrequired.

Interventional Recanalization of Artificial Arteriovenous Fistula and Graft for Hemodialysis: Angioplasty andPulsed-Spray Thrombolysis with Urokinase

PURPOSE: To evaluate the effectiveness of percutaneous transluminal angioplasty (PTA) and pulsed-spraypharmacomechanical thrombolysis (PSPMT) using urokinase for the management of insufficient hemodialysis access. MATERIALS AND METHODS: Between September 1996 and May 1998, 21 insufficient hemodialysis accesses were treated in16 patients (3 artificial arteriovenous fistulae, AVF ; and 13 arteriovenous graft, AVG). PTA and PSPMT were performed in 6 and 15 and 15 cases, respectively, and success and long-term patency rates were evaluated. RESULTS: The overall success rate of PTA and PSPMT for insufficient hemodialysis access was 76.2%(16/21). The success rates of PTA and PSPMT were 83.3%(5/6) and 73.3%(11/15), respectively. the primary patency rates of PSPMT were 69+/-12.8% at 6 months and 38+/-18.6% at 12 months. One of the two initially successful PTAs had been patent for 7months, and the second PTA was performed at that time due to venous stenosis. The other was patent for 15 months throughout the follow-up period. CONCLUSION: PTA and PSPMT are effective primary methods for the treatment of insufficient hemodialysis access ; success and patency rates were high, and the procedures can be performed repeatedly.

Radiologic Findings of Pulmonary Endometriosis

PURPOSE: To evaluate the effectiveness of percutaneous transluminal angioplasty (PTA) and pulsed-spraypharmacomechanical thrombolysis (PSPMT) using urokinase for the management of insufficient hemodialysis access. MATERIALS AND METHODS: Between September 1996 and May 1998, 21 insufficient hemodialysis accesses were treated in 16 patients (3 artificial arteriovenous fistulae, AVF ; and 13 arteriovenous graft, AVG). PTA and PSPMT were performed in 6 and 15 and 15 cases, respectively, and success and long-term patency rates were evaluated. RESULTS: The overall success rate of PTA and PSPMT for insufficient hemodialysis access was 76.2%(16/21). The success rates of PTA and PSPMT were 83.3%(5/6) and 73.3%(11/15), respectively. the primary patency rates of PSPMT were 69+/-12.8% at 6 months and 38+/-18.6% at 12 months. One of the two initially successful PTAs had been patent for 7months, and the second PTA was performed at that time due to venous stenosis. The other was patent for 15 months throughout the follow-up period. CONCLUSION: PTA and PSPMT are effective primary methods for the treatment of insufficient hemodialysis access ; success and patency rates were high, and the procedures can be performed repeatedly.

Experimental Model of Arteriovenous Fistula in Pigs

PURPOSE: To establish an experimental model of arteriovenous fistula in pigs. MATERIALS AND METHODS: Ten fistulas were created in eight pigs, and angiography was performed 3 to 5 days after surgery. A follow-up angiogram of three fistulas was obtained 2 to 12 weeks later. In one animal, pathologic examination showed occlusion 8 weeks after a successful operation. RESULTS: Eight angiograms of nine fistulas in seven pigs were obtained; one animal died due to cardiac failure. In six pigs, high-flow fistulas were shown to be present, and in two, the fistulas were slow flow; a pseudoaneurysm was seen in one. A follow-up angiogram obtained in three cases showed occlusion of the fistula. Pathologic examination of one animal showed fibrosis in the occluded portion of the fistula. CONCLUSION: An arteriovenous fistula model was surgically established in 80% of cases; during follow-up, three fistulas were seen to be occluded due to fibrosis. This model can therefore be used within one week of surgery.

Percutaneous Transluminal Angioplasty and Thrombolysis in the Management of Insufficient Hemodialysis Access: Long-Term Patency Rates and Factors Affecting Patency Rates

PURPOSE: To evaluate the success rates, long-term patency rates and factors affecting the patency rates of percutaneous transluminal angioplasty (PTA) and thrombolysis in the management of insufficient access during hemodialysis. MATERIALS AND METHODS: Between January 1991 and March 1995, 37 insufficient shunts (23 native fistulae and 14 graft fistulae) were treated in 31 patients. PTA was performed in 24 shunts, and thrombolysis in13; in seven of these latter, thrombolysis was followed by PTA. The success and long-term patency rates of PTA and thrombolysis were evaluated. Shunts were subdivided according to a patient's age, type and age of the shunt, and number and length of the stenosis, and the degree of residual stenosis and in each subgroup, patency rates was compared. RESULTS: The overall success rate of PTA and thrombolysis for insufficient hemodialytic access was 78.4% (29/37). The success rates of PTA and thrombolysis were 91.7% (22/24) and 53.8% (7/13), respectively. The patency rates of PTA (85.7% at 6 months, 78.6% at 12 months, and 55.9% at 24 months) were superior to those of thrombolysis (100% at 6 months and 0% at 12 months) (p=.014). Patency rates in each subgroup were not significantly different (p>.05). CONCLUSION: The success and patency rates of PTA were superior to those of thrombolysis, and after PTA or thrombolysis, no factors affected patency rates.

MR Imaging of Intracranial Dural Arteriovenous Fistulae (Dural AVF)

PURPOSE: To describe the magnetic resonance (MR) findings of intracranial dural arteriovenous fistulae (DAVF) and associated venous hypertensive diseases, and to determine their diagnostic value. MATERIALS AND METHODS: MR Imagings of twelve cases of angiographically-proven intracranial DAVF were analyzed. The presence of signal voids, dilatation of involved dural sinus, the dilatation of the extra/intradural venous system, high signal intensity on T2 weighted image, cerebral edema, intracranial hemorrhage, and hydrocephalus were retrospectively analyzed. MR findings and angiographic classification were compared. RESULTS: In 11 of 12 patients (92%), MR revealed the location of DAVF. In five cases, these were cavernous, and in six, they were extracavernous; the locations of the latter were as follows: superior sagittal sinus (SSS), 4: torcula, 1; lateral sinus & SSS, 1. Except for the lateral sinus lesion, all the DAVF seen in thses 11 patients showed the presence of signal voids and dilatation of the involved dural sinus. Findings of associated venous hypertensive disease, namely dilatation of the superior ophthalmic vein and cortical venous system, cerebral edema, and high signal intensity on T2-weighted images were observed in three cavernous lesions (50%), but all extracavernous DAVF (100%) showed associated venous hypertensive disease. When the grade of angiographic classification was high and reflux of sinus blood to the cortical vein was seen on angiography, the MR findings of intracranial venous hypertension showed good correlation. CONCLUSION: The MR findings of DAVF include dilatation of the dural sinus and signal voids of feeding arteries and draining vein. Other findings which suggest intracranial venohypertensive disease are dilatation of the cortical and medullary vein, hydrocephallus, cerebral edema and intracranial hamorrhage. These and the angiographic findings correlate well and suggest that in the diagnosis of DAVF and the detection of intracanial venohypertension, MR is a non-invasivse technique which can be use be usefully employed before final diagnosis by angiography.