Neovascularization after great saphenous vein ablation.

OBJECTIVE: To determine the prevalence, distribution, and flow characteristics of intraluminal neovascularization in patients undergoing great saphenous vein (GSV) endovenous laser (EVLT) or radiofrequency ablation (RFA). METHODS: Duplex ultrasound (DU) was performed in patients undergoing EVLT or RFA before, during, and after their procedures. Follow-up included assessment for deep venous thrombosis and obliteration. When new vessels were identified, the source, extent, direction, and location of flow were noted. Flow channel diameters were measured and the resistivity index (RI) was used to characterize the flow patterns. RESULTS: A total of 102 venous ablations were performed of which 46 were RFA, and 56 EVLT. Arterio-venous fistulae (AVF) were found in five patients that were not identified by DU prior to intervention. Involved segments had variable length and multiple channels (mean diameter 2.2mm). No patient had local or systemic symptoms related to the AVF. The mean RI was 0.42, consistent with an AVF. The perivenous arteries feeding the AVF had enhanced flow but a significantly higher RI (0.63, p<0.001). CONCLUSION: Multiple small vessels were found directly adjacent to the involved vein segments forming small AVF within the obliterated vein. The prevalence of AVF in the ablated GSV was 5%. This process may be responsible for recanalization or recurrence after endovenous ablation procedures.     

Side-to-side arteriovenous fistula at the elbow with perforating vein ligation

OBJECTIVE: We postulated that ligation of a consistent perforating venous branch at the elbow would improve distention and flow in the superficial veins about the elbow. This would also lesson the likelihood of arterial steal enabling a favorable outcome following a brachial artery medial antecubital or cephalic vein arterio-venous fistula (AVF). METHODS: Pressure measurements were made from the radial artery after side-to-side brachial artery antecubital or cephalic vein AVF in 20 patients. Clamping of the perforating vein increased radial artery pressure significantly indicating that a considerable amount of flow from the side-to-side AVF was diverted into the deep system and away from the accessible superficial veins. Encouraged by this finding, we studied the outcome of brachial cephalic or brachial antecubital AVF with ligation of the deep branch in 134 patients who were not candidates for radio-cephalic AVF. The end point of the study was successful hemodialysis using the fistula. RESULTS: Of the 134 patients treated, 24 died, and 11 were lost to follow-up and were censored from analysis of fistula performance at that time point. The primary fistula success rate was 89.7% +/- 2.66% and 83.7% +/- 3.5% at 1 and 2 years by life table analysis. No patient developed significant arterial steal or venous hypertension. CONCLUSION: We recommend this simple one-stage procedure for patients requiring hemodialysis whose cephalic vein at the wrist is unsuitable.     

Sheep Model of Hemodialysis Arteriovenous Fistula Using Superficial Veins

Current models of animal arteriovenous fistula (AVF) are swine models of femoral vein terminolaterally anastomosed to femoral artery, creating a deep AVF. This feature sets it aside from human AVFs using superficial veins. Our AVF model uses sheep superficial veins to create an AVF almost identical to human model. AVFs were created in six sheep using basilic veins sutured terminolaterally to brachial artery. Presurgery vein and artery diameters were measured. We measured AVFs and feeding arteries blood flows and diameters at 1, 3, and 5 weeks postsurgery. At 5 weeks we performed angiograms, euthanized animals, and harvested AVFs. Four animals completed the study. Three AVFs developed and were patent at 5 weeks; one thrombosed. Animal weight and presurgery vessels diameters predicted AVFs blood flows and diameters. Despite using vessels with diameters smaller than the ones recommended for human AVF, the Fistulas developed. Two animals died before the study conclusion for causes unrelated to surgery. This AVF model is anatomically almost identical to the human AVF and has a good maturation rate. It is a viable model for studying AVF maturation, devices intended to improve AVF maturation, AVF related procedures and can even support hemodialysis needles.     

Importance of valvular incompetence after acute deep venous thrombosis.

The color Doppler scanner was used to analyze acute deep venous thrombosis in 14 patients. A thrombus was found in the superficial femoral vein in 4 patients and in the superficial femoral and popliteal veins in 6 patients; a popliteal occlusion was found in 4 patients. All 14 patients were treated with intravenous heparin followed by at least 3 months of warfarin therapy. Patients were re-examined between 24 and 48 months. Six patients were symptomatic; 8 were asymptomatic. Five patients had occluding thrombus in the distal popliteal vein; major competent collateral channels developed from the proximal superficial femoral vein, and they remained asymptomatic. Three patients whose superficial femoral veins recanalized without valvular incompetence were asymptomatic. Valvular incompetence was observed in all of the symptomatic patients. Patients with persistent popliteal occlusion and collateral channels have fewer symptoms than patients with valvular incompetence in the superficial femoral and popliteal veins.     

Late symptomatic venous stenosis in three hemodialysis patients without previous central venous catheters

It is well known that catheters placed in the subclavian or internal jugular veins may develop stenosis in the vein in which the catheter lies. Because the arteriovenous fistula (AVF) relies on good venous outflow, patients with ipsilateral central venous stenosis are subject to the malfunctioning of AVF. Until now, no data were published on patients showing central vein stenosis (CVS) without a previous central venous catheter (CVC) or a pacemaker. In this article, we report on 3 hemodialysis patients manifesting CVS ipslateral to AVF. None of these patients previously had undergone CVC. The stenosis observed had characteristics and symptoms similar to those observed in stenoses consequent to CVC. We concluded that CVS also may occur in subclavian or axillary veins proximal to a working AVF in hemodialysis patients who have never had a CVC and in the absence of compressive phenomena.     

Exclusively epidural arteriovenous fistula in the cervical spine with spinal cord symptoms: case report

OBJECTIVE AND IMPORTANCE: We describe the case of an epidural arteriovenous fistula (AVF) in the cervical spine draining only into the epidural and paravertebral plexus. An entirely epidural AVF having such drainage is extremely rare. CLINICAL PRESENTATION: A 24-year-old man presented with a 4-month history of gradually progressive sensory and motor disturbances of the upper and lower extremities. Magnetic resonance imaging and magnetic resonance angiography revealed a peridural vascular lesion within the canal compressing the spinal cord from C5 to T2. Diagnostic angiography revealed a perimedullary and/or dural high-flow AVF, fed mainly by branches of ascending cervical and deep cervical arteries. The fistula drained into the epidural and paravertebral venous plexus without reflux into intradural venous systems. INTERVENTION: Multiple feeders of the AVF were embolized with a Liquid coil and n-butylcyanoacrylate via a two-step procedure. One week after embolization, the AVF was surgically removed. CONCLUSION: Interesting points of this case were the exclusively epidural location of the lesion, the exclusively epidural drainage of the AVF, and the etiology of the symptoms. Venous drainage of the fistula had no relation to any dural or intradural veins. Initially, spinal cord and nerve root compression by extradural veins with varicose dilation seemed to cause the radiculopathy and/or the myelopathy, and subsequent myelopathy caused by spinal venous hypertension was believed to be the main etiology in this case.     

Atypical dural arteriovenous fistula associated with meningitis

A 49-year-old male presented with hemisensory disturbance and gait unsteadiness following a previous episode of meningitis. He had no contributory medical or head injury history. Magnetic resonance imaging revealed innumerable medullary vessels in the white matter of the left cerebral hemisphere, which had not been recognized in the previous imaging study. Cerebral angiography showed variant superior sagittal sinus (SSS) arteriovenous fistula (AVF) fed by the bilateral middle meningeal and superficial temporal arteries, and drained directly to the cortical veins with marked venous engorgement in the affected hemisphere. The fistulas were located on the cortical veins, apart from the SSS. Initial percutaneous transarterial embolization failed, so the AVF was completely obliterated with a combination of surgical and endovascular techniques. The symptoms ameliorated postoperatively. Meningitis may be an underlying pathology of dural AVF. Variant SSS AVF can be treated with a combination of surgical and endovascular techniques.     

Iliofemoral venous thrombectomy followed by percutaneous closure of the temporary arteriovenous fistula

Iliofemoral venous thrombosis treated by anticoagulants alone almost invariably results in postthrombotic sequelae with deep venous reflux alone or combined with an outflow obstruction. This study evaluates the result of iliofemoral venous thrombectomy with temporary proximal arteriovenous fistula (AVF) performed on 48 consecutive patients. In 10 patients the thrombus extended in the inferior vena cava, and the thrombectomy was combined with inferior vena cava interruption. The AVF closed spontaneously in 8 of 48 patients (patency rate, 84%). An attempt to close the AVF by placing a detachable balloon percutaneously under radiographic control was made 6 to 12 weeks later (success rate, 87%; complications, rare). A preclosure arteriovenography of the femoro-iliaco-caval segment revealed 34 of 38 segments open (patency rate, 89%). Four patients had severe stenosis of the iliac segment, and a transvenous percutaneous dilatation was successfully performed in three of the four patients, keeping the fistula. At AVF closure 4 weeks later the arteriovenography showed sustained dilatation in only two patients. Thirty-seven patients were followed for 3 to 48 months (median, 24 months) and 30 of 37 patients (81%) who had no symptoms were not using compression stockings. Doppler investigation revealed patent and competent femoral and popliteal veins and normal photoplethysmography in 56% of the patients. Four iliac veins were occluded (patency rate, 88%). No recurrence of fistula had occurred. Venous iliofemoral thrombectomy seems to better preserve valve function. The percutaneous balloon closure of the AVF has decreased the complication rate, facilitated venographic evaluation of the result, and made possible the performance of percutaneous interventions under the protection of the AVF.     

On the Phenomenology of the Perforating Vein of the Elbow

The perforating veins, as the name suggests, are the veins that perforate the muscular aponeuroses ensuring communication between the superficial and the deep veins. Located at the bend of the elbow, almost constantly, there is a vein, named perforating vein of the elbow, which is of great interest to the nephrologist who is responsible for the management of vascular access for hemodialysis (HD). It represents, in fact, because of its intrinsic characteristics and topographical reasons, a valuable resource for the creation of a vascular access for HD, especially in obese patients, elderly patients, diabetics, and patients affected by peripheral vasculopathy. Arterio-venous fistulae (AVF) constructed with the perforating vein of the elbow are relatively easy to perform, have an excellent patency rate, a low incidence of early thrombosis, adequate flows, and a low incidence of the steal syndrome. In other types of AVFs, the perforating vein of the elbow subtracts flow to the superficial veins slowing or preventing their full maturation, and can become a problem in measuring the blood flow of the AVF. But still, its presence can maintain patent a fistula in case of poor compliance of the superficial veins, while awaiting for interventional procedures able to accelerate a subsequent maturation. This review intends to explore the role that the perforating vein of the elbow plays in the physiology and pathology of the AVF, in relation to the issues that most frequently occur in clinical practice.     

Spontaneous thrombosis of a spinal conus perimedullary arteriovenous fistula. Case report

A 49-year-old male presented with a rare case of acute lower extremity paresis caused by spontaneous thrombosis of a spinal conus perimedullary arteriovenous fistula (AVF) after a subacute myelopathic course. Magnetic resonance imaging obtained after deterioration showed that the flow voids around the conus medullaris had changed from hypointense to hyperintense lesions. Surgery with thoracic laminoplasty was performed to determine the nature of the lesion because angiography was negative. During surgery, thrombosed abnormal vessels were observed, consistent with thrombosis of a spinal conus perimedullary AVF. Histological specimens of the thrombosed vessels exhibited vascular wall injury such as intimal alteration, wall dissection, and mural thrombus. Hemorrhage and infection were excluded. Vascular wall injury of draining veins and varices were probably one of the causes of thrombosis in the present case. Spinal arteriovenous malformation generally causes progressive venous congestive myelopathy, but the congestive myelopathy may rarely rapidly deteriorate with spontaneous thrombosis, known as Foix and Alajouanine syndrome.     

Color Doppler US Evaluation of Feeding Artery after Balloon Angioplasty of the Drainage Vein in Dysfunctional Hemodialysis AVF

Purpose.?The aim of this study was to investigate flow rate and resistive index (RI) parameters of the feeding artery after balloon angioplasty of the drainage vein in dysfunctional hemodialysis arteriovenous fistula (AVF) due to venous stenosis/thrombosis.?Methods.?A cohort of 10 patients with native dysfunctional hemodialysis AVF was evaluated prospectively. Three of the 10 patients had a thrombosed drainage vein, and the remaining seven patients had a stenotic drainage vein. Flow rate and RI of the feeding artery of AVF were calculated by Color Doppler ultrasound (CDU) before and after balloon angioplasty and in the follow-up period. The flow rates and RI values before and after angioplasty and in the follow-up were compared.?Results.?Increased flow rate and decreased RI values were detected after balloon angioplasty in all patients. We detected restenosis or thrombosis of drainage vein in six of the patients in the follow-up period. Decreased flow rate and increased RI values compared with previous measurements were calculated in these patients.?Conclusions.?Increased flow rate and decreased RI in the feeding artery of native dysfunctional AVF were demonstrated in patients who underwent balloon angioplasty on the stenotic vein. If restenosis develops in the follow-up period, the previous high resistance flow pattern is observed again. Feeding artery flow parameters as calculated by CDU can be used as a simple indicator of possible drainage vein problems of native AVF.     

Subarachnoid hemorrhage caused by dural arteriovenous fistula of the sphenobasal sinus--case report

A 59-year-old woman presented with a rare middle fossa dural arteriovenous fistula (AVF) unrelated to the cavernous sinus manifesting only as subarachnoid hemorrhage. Angiography revealed shunts between the meningeal branches of both the internal and external carotid arteries and the sphenobasal sinus. The AVF drained into the superficial middle cerebral vein (SMCV) which had a varix and an anastomosis to a superior cerebral vein. The arterial supply vessels were eliminated surgically and the sinus was excised. Bleeding did not recur and there was no venous infarction. Dural AVF of the sphenoparietal sinus is associated with pulsatile exophthalmos and dural AVF of the sphenopetrosal sinus with tinnitus, but dural AVF of the sphenobasal sinus has no obvious symptom. Simple interruption of the SMCV at the penetration of the arachnoid membrane was possible because of the absence of a draining vessel to preserve AVF patency, but the arteries were eliminated in this patient to prevent formation of another AVF.     

Interventionalist's role in identifying candidates for secondary fistulas

One hundred consecutive patients with upper extremity prosthetic grafts referred for either an angioplasty or treatment of a thrombosed graft were included in the study. After the patient's treatment was concluded, the angiographic images that had been created during the case were evaluated to determine if an upper arm vein was evident that would be suitable for the construction of an arteriovenous fistula (AVF). Criteria used to determine suitability included vein size measured at the level of the elbow, feeding artery size at the level of the elbow, absence of stenosis within the vein, and continuity with downstream unobstructed veins. Thirty-eight percent of patients had an upper arm graft and 62% had a lower arm graft. Since it was not possible to adequately evaluate patients with an upper arm graft, these patients were not included in any further evaluations. A total of 46 patients (74%) with a forearm loop graft had one or both of the upper arm veins that appeared to be optimum for the creation of an AVF. If the percentage of graft patients with venous anatomy conducive to the creation of a fistula revealed in this study is representative, then the percentage of fistulas in use could be very quickly increased to more than 50% by simply seizing the opportunity. This effort directed toward prevalent patients could yield results much more rapidly than limiting one's focus to incident patients.     

Paravertebral arteriovenous fistula treated by endovascular coil embolization

A 41-year-old man, without underlying health problems or traumatic episodes, presented with a rare paravertebral arteriovenous fistula (AVF) causing radiculopathy manifesting as gradually progressive right grip weakness, and right thumb, index, and middle finger numbness. Digital subtraction angiography revealed a high flow, single hole paravertebral AVF fed by the right thyrocervical trunk that drained into the epidural venous plexus. The patient underwent endovascular embolization of the AVF via the transarterial approach. The fistula was completely occluded by coil embolization. Postembolization, clinical symptoms improved and 6-month follow-up angiography showed no recurrence of the fistula. Paravertebral AVF is a rare vascular malformation occurring outside the dura mater, fed by dural or epidural branches, and draining primarily into the epidural venous plexus. Paravertebral AVF is usually asymptomatic because of a "reflux-impending mechanism" within the dural sleeves that prevents retrograde drainage into the perimedullary veins. However, in the present case, mechanical compression of the radicular nerve due to a dilated epidural venous plexus resulted in neurological symptoms. We conclude that endovascular surgery is an effective treatment strategy for paravertebral AVF.     

Flow velocity and pressure measurements in spinal dural arteriovenous fistulas

During ten operations for spinal dural arterio-venous fistulas (AVF), intraoperative measurement of flow velocity and intravascular pressure was performed. Flow velocities were recorded using a miniaturized Doppler probe. Intravascular pressure changes in the draining veins beofre and after AVF removal was measured with small needles. Varying the pCO₂ between 20 mm Hg and 60 mm Hg, the flow velocities in arteries supplying the spinal cord were investigated so that the vasomotoric reactivity of the peripheral vessel wall in cord tissue was investigated before and after AVF occlusion. The flow velocities in dural AVF feeders were not as high as those known from cerebral angioma feeders. In addition, they often showed lowered end-diastolic flow velocity as a dign of increased vascular resistance, thus proving impaired venous outflow from the spinal canal. After excision of the local fistula, the vessels supplying and draining the spinal cord showed improved circulation. In the former recipient veins, no further flow could be recorded.The venous pressure in dural AVF was about 70% of the systemic arterial pressure. Fistulas presenting a high shunt volume on angiography showed only moderately increased venous pressure and a more pronounced pressure drop after fistula occlusion as compared with low-volume fistulas. The CO₂ reactivity of vessels supplying the spinal cord was normal before and after AFV removal.     

A comparative experimental study of the organization of arterial and venous thrombi.

Organization of a venous thrombus proceeds much faster than that of an arterial thrombus. Two different double-ligation procedures were used for study of the time sequence of thrombus organization by the vascularized (in situ) and devascularized (dissected) walls of the external jugular vein and common carotid artery in 21 mongrel dogs. Blood in the ligated segments of the in situ veins remained mostly fluid. In these segments, intimal hyperplasia was observed after 4 weeks with apparent preservation of an endothelial lining. However, in the dissected veins, the trapped blood rapidly thrombosed. Remarkable cell proliferation quickly occurred in these dissected walls with rapid invasion of the thrombus to achieve complete organization by 4 weeks. In contrast, a thrombus formed in the ligated segments of all arteries, whether in situ or dissected, and organization was much slower, requiring about 4 months for completion. Full-wall viability was maintained in 100% of the in situ veins and in 95% of the devascularized veins, but inner wall viability was lost in 30% of the in situ arteries and in 95% of the devascularized arteries.     

创伤性动静脉瘘20例的手术治疗

目的：探讨创伤性动静脉瘘(arteriovenous fistula,AVF)的手术方法。方法：回顾性分析了：1989年1月至2001年8月经手术治疗的创伤性AVF20例，共23个动静脉瘘。分别采用四头结扎术2例；经静脉切开修补瘘口3例；经动脉切开修补瘘口、重建动脉血流8例；瘘切断、动静脉壁瘘口侧面修补术1例；经瘤腔同时修补动静脉瘘口1例；经瘤腔修补静脉瘘口、动脉结扎或大隐静脉移植2例；瘘管结扎术3例。结果：死亡1例，随访16例，2例复发，2例肢端慢性溃疡者效果欠佳，余效果良好。结论：创伤性AVF应早期手术，根据分型采用不同手术方法，效果良好。     

Arteriovenous fistulas as an adjunct to venous surgery

The objectives of the temporary arteriovenous fistula (AVF) are to increase blood flow in the thrombectomized segment to prevent immediate thrombosis and to allow time for healing of the endothelium. After complete thrombectomy of the iliac vein, confirmed by intraoperative venogram, the AVF is constructed using the divided long saphenous vein end-to-side to the superficial femoral artery. After 6 to 8 weeks, the patency of the AVF and the deep venous system is assessed by duplex scan, followed by an arteriovenogram from the opposite femoral artery, evaluating the anatomy of the AVF, common femoral vein, iliac vein, and the inferior vena cava (IVC). The AVF is closed using coils.     

Femoral arteriovenous fistula as a complication of percutaneous transluminal coronary angioplasty. A report of five cases

Arteriovenous fistula (AVF) associated with invasive and diagnostic angiographic procedures is rare. The incidence is increased with procedures such as percutaneous transluminal coronary angioplasty (PTCA) but is still quite low. We report five cases of AVF within a 17-month period, representing 0.15 per cent of all cardiac catheterizations and 0.87 per cent of PTCAs. All five patients presented with groin bruits. There were two associated pseudoaneurysms and one patient with deep vein thrombosis. All patients underwent uneventful division of the fistula. A thorough understanding of the anatomy of the femoral triangle is necessary in order to avoid this complication. That all fistulas were in the superficial or profunda femoris arteries emphasizes the importance of avoiding a low groin puncture. Early angiography and surgical intervention are recommended for optimal results.     

Progressive myelopathy caused by dural arteriovenous fistula at the craniocervical junction--case report.

A 68-year-old male presented an unusual dural arteriovenous fistula (AVF) located at the craniocervical junction. Magnetic resonance imaging revealed dilated perimedullary veins around the spinal cord at C-1 and C-2 levels, as well as high intensity signals in the spinal cord on T2-weighted images. Vertebral angiography identified an AVF at the point where the right vertebral artery penetrates the dura. The fistula was a single and direct communication between the vertebral artery and the spinal vein. Surgical interruption of the fistula at its venous side resulted in prompt improvement of both motor and sensory signs and symptoms.