Perioperative stroke during carotid endarterectomy: benefits of multimodal neuromonitoring - a case report.

BACKGROUND: Carotid endarterectomy is routinely performed after ischemic stroke due to carotid stenosis. Perioperative, cerebral blood flow and oxygenation can be monitored in different ways, but there is no clear evidence of a gold standard and a uniform guideline is lacking. Electroencephalography and near-infrared spectroscopy are among the most frequently used methods of neuromonitoring. Clinicians should be aware of their pitfalls and the added value of transcranial doppler. CASE PRESENTATION: We present the case of an 85-year old male with perioperative haemodynamic stroke during carotid endarterectomy. Ischemic stroke was caused by suddenly increased carotid stenosis resulting in major neurologic deficit. This was registered only by transcranial doppler, while surface electroencephalography and near-infrared spectroscopy failed to detect any significant change in cerebral perfusion, despite a large perfusion defect on computed tomography. Circulation was restored with endovascular treatment and neurologic deficit quickly resolved. CONCLUSION: We strongly advocate the practice of multimodal neuromonitoring including transcranial doppler whenever possible to minimize the risk of persistent neurologic deficit due to perioperative stroke during carotid endarterectomy.

Case report: direct revascularization in acute mesenteric ischemia by an endovascular approach.

BACKGROUND: Acute mesenteric ischemia is a relatively rare but life-threatening clinical condition. Outcome depends on early diagnosis and prompt intervention. CASE PRESENTATION: A 85-year-old man and a 75-year-old woman developed acute mesenteric ischemia due to cardiac embolism. The first patient received an insufficient dose of anticoagulants for atrial fibrillation and the second patient dicontinued her anticoagulantia to avoid bleeding during a routine colonoscopy. Both patients presented with severe abdominal pain and computed tomography showed thrombus in de superior mesenteric artery. Successfulrevascularization with good clinical outcome was achieved by means of an endovascular first approach. CONCLUSION: This case report shows that an endovascular approach - in contrast to open surgery - not only enables to revascularize main trunk lesions but can also facilitate revascularization of side branches. Endovascular treatment used to be limited to a selected group of patients without signs of bowel necrosis, but there is a tendency to initiate endovascular revascularization in all patients because it is associated with a reduced mortality, a reduced laparotomy rate and reduction in the resected length of bowel.

Predictors of Failure of Closure in Percutaneous EVAR Using the Prostar XL Percutaneous Vascular Surgery Device.

OBJECTIVE: To identify predictors of failure in percutaneous endovascular aneurysm repair (P-EVAR) using the Prostar XL Percutaneous Vascular Surgery Device (Abbot Vascular, Santa Clara, CA, USA) and the need for conversion to conventional femoral cutdown (O-EVAR). METHODS: Consecutive patients who underwent P-EVAR with the Prostar XL device between January 2009 and April 2012 were included in this series. Patients with a circular calcified common femoral artery (CFA) oncomputed tomography angiography were operated using O-EVAR and were therefore excluded. To identify predictors of success of closure in P-EVAR, artery characteristics, sheath size used, and comorbidities were analyzed in a univariate logistic regression model. RESULTS: Percutaneous access was achieved in 154 femoral access sites with conversion to O-EVAR was needed in10 (6.5%). Significant predictors of conversion included sheath size (continuous, relative risk [RR] 1.50, p < .03)and the ratio between sheath size and CFA diameter >0.75 (RR 8.93, p < .01). Variables such as calcification quantity scores, CFA diameter, body mass index, and comorbidities were not significant. CONCLUSION: The data demonstrate that sheath size, in particular, combined with CFA diameter predicts failure of closure in P-EVAR using the Prostar XL device. This ratio can be utilized to help in decision making with regard to the EVAR approach. A ratio of >0.75 would favor a primary open groin approach.

A comparative study of myocardial injury during conventional and endovascular aortic aneurysm repair: measurement of cardiac troponin T and plasma cytokine release.

BACKGROUND: Major aortic surgery results in significant haemodynamic and oxidative stress to the myocardium. Cytokine release is a major factor in causing cardiac injury during aortic surgery. Endovascular aortic aneurysm repair (EVAR) has the potential to reduce the severity of the ischaemia reperfusion syndrome and its systemic consequences. AIM: The aim of this study was to investigate the occurrence of myocardial injury during conventional and endovascular abdominal aortic aneurysm repair using measurement of the myocardial-specific protein, cardiac troponin T. Interleukin-6 was also measured in both groups and haemodynamic responses to surgery assessed. METHODS: Nine consecutive patients undergoing conventional infra-renal aortic aneurysm surgery were compared with 13 patients who underwent EVAR. Patients were allocated on the basis of aneurysm morphology and suitability for endovascular repair. RESULTS: Patients undergoing open repair had significantly more haemodynamic disturbance than those having endovascular repair (mean arterial pressure at 5 min following unclamping or balloon deflation: open (69.6 + 3.3 mmHg); endovascular (86 + 4.4 mmHg), P < 0.05 vs. pre-op). Troponin T levels at 48 h post-operatively were higher in patients who underwent open repair (open 0.164 + 0.1 ng/ml; endovascular 0.008 + 0.0005 ng/ml, P < 0.04). Significantly more patients in the open repair group had troponin T levels > 0.1 ng/l when compared with the endovascular group (P < 0.01, chi (2) test) CONCLUSION: Endovascular aortic surgery produces significantly less myocardial injury than the open technique of aortic aneurysm repair.

Shrinkage of abdominal aortic aneurysm after successful endovascular repair: results from single center study.

AIM: In the literature, the behavior of the aneurysm sac after endovascular grafting has been the subject of significant speculation. It has been suggested that shrinkage of the abdominal aortic aneurysm (AAA) is different for various endografts. This study was undertaken to evaluate endograft-specific differences in aneurysm sac shrinkage and to evaluate other factors that may influence AAA shrinkage. METHODS: Forty patients with an AAA treated with endovascular grafts with a complete 18 months follow-up and complete CT angiography (CTA) follow-up were available for analysis. All patients with a persistent endoleak, endograft migration or any other reason for intervention or conversion were excluded from this analysis. Shrinkage was defined as a reduction in the AAA diameter of 5 mm or more. Chi-squared tests were used to test whether shrinkage was different for the kind of stent graft used (Gore Excluder vs Cook-Zenith), preexistent AAA diameter (<65 mm vs =or>65 mm), and AAA status (ruptured vs non-ruptured) (two-sided; a= 0.05). RESULTS: At 18 months after treatment, shrinkage was observed in 14 patients (52%) of the 27 patients treated with a Gore Excluder endograft and in 8 patients (62%) of the 13 patients treated with a Cook Zenith endograft (P=0.74). In 31 patients with a diameter <65 mm, shrinkage was observed in 19 patients (61%) whereas of the 9 patients with a diameter =or>65 mm, shrinkage was observed in 3 patients (33%) (P=0.253). Of the 34 patients with a non-ruptured AAA, shrinkage was observed in 18 patients (53%) versus of the 6 patients with a ruptured AAA shrinkage was observed in 4 patients (66%) (P=0.673). CONCLUSIONS: From this study can be concluded that the influence of the endograft on shrinkage of the AAA sac might be less prominent than suggested in the literature. Furthermore, our study shows that other factors such as preexistent AAA diameter may influence AAA shrinkage after endovascular repair.

[Complications within 30 days following placement of a carotid stent with cerebral protection in patients with considerable symptomatic carotid stenosis; Erasmus MC, Rotterdam, 1999-2004]. / Complicaties in de eerste 30 dagen na plaatsing van een carotisstent met cerebrale bescherming bij pati nten met een aanzienlijke, symptomatische carotisstenose; Erasmus MC, Rotterdam, 1999-2004.

OBJECTIVE: To describe the complications that occur within 30 days following the placement of a stent in the carotid artery in patients with considerable symptomatic carotid stenosis. DESIGN: Retrospective. METHOD: Data were collected on 98 patients who received a carotid stent due to symptomatic carotid stenosis of > or = 70% of the lumen at the Erasmus MC, Rotterdam, the Netherlands, in the years 1999-2004. A filter, distal occlusion balloon or the Parodi anti-embolism system was used to prevent cerebral embolism. Outcome measures were complications within 30 days following intervention. RESULTS: Four patients were excluded in the period between diagnosis and stenting. Major complications occurred in 3 patients: 1 died due to cerebral haemorrhage and 2 experienced cerebral infarction. Transient neurological complications occurred in 4 patients who recovered completely. Dissection of the renal artery occurred in 1 patient, which necessitated a stent. Vascular damage of the internal carotid artery was not observed in any patient. The 3 major adverse events and 3 of the 4 minor adverse events occurred in the first 47 patients treated. None of the last 47 patients treated developed major adverse events.

Cerebral protection during percutaneous carotid intervention: wich device should be used ?

Embolic complications remain the major and unpredictable clinical event during carotid angioplasty and stenting. Cerebral protection devices could play an important role in the prevention of such emboli. Protection devices such as occlusion balloons, filters and reversed flow devices are currently undergoing clinical evaluation and appear to be promising in reducing the incidence of embolic events. This article provides an overview of the three different types of embolic protection devices.

Shrinkage of the distal renal artery 1 year after stent placement as evidenced with serial intravascular ultrasound.

The objective of this study was to determine the quantitative intravascular ultrasound (IVUS) and angiographic changes that occur during 1 year follow-up after renal artery stent placement, given that restenosis continues to be a limitation of renal artery stent placement. 38 consecutive patients with symptomatic renal artery stenosis treated with Palmaz stent placement were studied prospectively. IVUS and angiography were performed at the time of stent placement and at 1 year follow-up. At follow-up, angiographic restenosis was seen in 14% of patients. The lumen area in the stent, seen with IVUS, was significantly decreased from 24+/-5.6 mm(2) to 17+/-5.6 mm(2) (p<0.001) solely due to plaque accumulation. The distal main renal artery showed a significant decrease in lumen area owing to a significant vessel area decrease from 39+/-14.0 mm(2) to 29+/-9.3 mm(2) (p<0.001) without plaque accumulation. Angiographic analysis confirmed this reduction in luminal diameter and showed that the distal renal artery diameter at follow-up was significantly smaller than before stent placement (86+/-23.0% vs 104+/-23.9% of the contralateral renal artery diameter; p=0.003). Besides plaque accumulation in the stent, unexplained shrinkage of the distal main renal artery was evidenced with IVUS and angiography 1 year following stent placement.

A precious metal alloy for construction of MR imaging-compatible balloon-expandable vascular stents.

The authors developed ABI alloy, which mechanically resembles stainless steel 316. The main elements of ABI alloy are palladium and silver. Magnetic resonance (MR) images and radiographs of ABI alloy and stainless steel 316 stent models and of nitinol, tantalum, and Elgiloy stents were compared. ABI alloy showed the least MR imaging artifacts and was more radiopaque than stainless steel 316. ABI alloy has the potential to replace stainless steel 316 for construction of balloon-expandable MR imaging-compatible stents.

Endovascular repair of an extracranial internal carotid artery aneurysm complicated by heparin-induced thrombocytopenia and thrombosis.

PURPOSE: To report the endovascular treatment of a symptomatic extracranial internal carotid artery (ICA) aneurysm that was complicated by heparin-induced thrombocytopenia and thrombosis. METHODS AND RESULTS: After undergoing a coronary artery bypass graft procedure, a patient was diagnosed with a symptomatic, 3.5-cm ICA aneurysm by computed tomography and angiography. Via a semiclosed access, an Enduring vascular graft was inserted under controlled back bleeding from the ICA. The patient was recovering uneventfully when routine duplex scanning on the fifth postoperative day suggested multiple thrombi within the graft, which was confirmed by arteriography. Thrombectomy and local fibrinolysis were performed; however, the graft occluded the next day without causing neurological symptoms. Heparin-induced thrombocytopenia was diagnosed by enzyme-linked immunosorbent assay. CONCLUSIONS: Endovascular repair of high cervical extracranial ICA aneurysms is feasible, and protection against intracerebral embolization can be achieved using a semiclosed technique with controlled back bleeding from the ICA during endograft deployment. However, multiple thrombi or thrombotic occlusion during the postoperative period, particularly in a patient already sensitized to heparin, should direct attention toward possible heparin-induced thrombocytopenia.

Three-dimensional intravascular ultrasound assessment of abdominal aortic aneurysm necks.

PURPOSE: To document the accuracy of an automated analysis system for measuring lumen diameter and neck lengths of abdominal aortic aneurysms (AAAs) from intravascular ultrasound (IVUS) images and to describe additional features associated with 3-dimensional (3D) IVUS imaging. METHODS: Twenty-two aortic aneurysms were studied with IVUS. Lumen diameters obtained using the automated analysis system were compared with manual measurements from axial IVUS scans, as were neck lengths obtained using automated analysis versus those measured with the aid of a displacement sensing device. Automated analyses were repeated by a second observer. Agreement was expressed as the coefficient of variation (CV). RESULTS: Twenty proximal aortic, 6 distal aortic, and 3 iliac necks were available for analysis. Comparison between automated analysis and manual measurements for lumen diameter revealed a difference of 0.45 +/- 0.42 mm (mean +/- SD, Pearson's r = 0.99, p < 0.001, CV = 2.1%) and a difference of 0.05 +/- 0.12 cm (r = 0.99, p = 0.04, CV = 4.1%) for neck length. Interobserver difference for lumen diameter was 0.13 +/- 0.66 mm (r = 0.99, p < 0.001, CV = 3.4%) and 0.05 +/- 0.11 cm for length measurements (r = 0.99, p = 0.02, CV = 3.5%). The 3D IVUS imaging facilitated the identification of neck configuration. CONCLUSIONS: Automated analysis of IVUS images allows accurate measurement of the lumen diameter of proximal and distal AAA necks and gives length measurements comparable to those of manual analysis. Longitudinal display of IVUS images aids in the elucidation of neck anatomy.

Stent placement for renal arterial stenosis: where do we stand? A meta-analysis.

PURPOSE: To perform a meta-analysis of renal arterial stent placement in comparison with renal percutaneous transluminal angioplasty (PTA) in patients with renal arterial stenosis. MATERIALS AND METHODS: Studies dealing with renal arterial stent placement (14 articles; 678 patients) and renal PTA (10 articles; 644 patients) published up to August 1998 were selected. A random-effects model was used to pool the data. RESULTS: Renal arterial stent placement proved highly successful, with an initial adequate performance in 98% and major complications in 11%. The overall cure rate for hypertension was 20%, whereas hypertension was improved in 49%. Renal function improved in 30% and stabilized in 38% of patients. The restenosis rate at follow-up of 6-29 months was 17%. Stent placement had a higher technical success rate and a lower restenosis rate than did renal PTA (98% vs 77% and 17% vs 26%, respectively; P <.001). The complication rate was not different between the two treatments. The cure rate for hypertension was higher and the improvement rate for renal function was lower after stent placement than after renal PTA (20% vs 10% and 30% vs 38%, respectively; P <.001). CONCLUSION: Renal arterial stent placement is technically superior and clinically comparable to renal PTA alone.

Peripheral vascular brachytherapy: an introduction.

The response of cells to ionising radiation has been extensively studied for the past 30 years. When radiation is absorbed in biological material, it can directly ionise a critical site (direct effect) or interact with other molecules to produce reactive free radicals, which can subsequently damage critical biological molecules (indirect effect). DNA is considered the critical target damaged by ionising radiation by both direct and indirect processes. Since radiotherapy had proven to be effective in the treatment of non-malignant proliferative processes, it was assumed that this adjunctive treatment would also inhibit vascular restenosis. The major difference between external and intravascular radiation is dose distribution. Intravascular delivery results in extremely high doses to the lumen with a fall-off in dose as a function of distance from the source; whereas, external beam would deliver a uniform dose over the entire volume of tissue treated. Unlike in the coronary circulation most of the peripheral vessels treated are greater than 3 mm in diameter; in fact many are 7 to 10 mm in diameter. Since beta radiation is related to lower penetration properties and more heterogeneous distribution of radiation in comparison to gamma radiation, it is therefore necessary to use a gamma radiation source because it would be difficult to irradiate the sub-intimal tissue with a beta source centred in a large vessel. Radiation can and does have the potential to destroy blood vessels. The challenge in vascular brachytherapy is to treat blood vessels to a point where restenosis is inhibited; yet the vessel is not irreparably damaged.

Ultrasound-guided percutaneous coil embolization of incompetent perforating veins: not effective for treatment of venous ulcers and recurrent varicosities.

PURPOSE: To investigate the feasibility of ultrasound-guided percutaneous coil embolization of incompetent perforating veins as minimally invasive treatment for venous ulcers and recurrent varicosities in the lower leg. This could be an alternative to surgical ligation of perforating veins. MATERIALS AND METHODS: In 15 patients (six women, nine men; mean age, 50 years), 18 incompetent perforating veins in the lower leg were treated by ultrasound-guided percutaneous placement of embolization coils. RESULTS: Successful vein occlusion with one or more coils was achieved in 12 of the 18 veins (technical success rate, 67%). Clinical symptoms improved in only three of the 15 patients (clinical success rate, 20%). During follow-up (2-12 months), recanalization of coil embolized veins occurred in nine of the 12 initially occluded veins. CONCLUSION: Percutaneous ultrasound-guided coil embolization does not appear to be as effective as subfascial endoscopic perforator surgery in the treatment of incompetent perforator veins.

Intravascular ultrasound evidence for coarctation causing symptomatic renal artery stenosis.

BACKGROUND: A recent study of human cadaveric renal arteries revealed that renal artery narrowing could be due not only to atherosclerotic plaque compensated for by adaptive remodeling, but also to hitherto undescribed focal narrowing of an otherwise normal renal arterial wall (ie, coarctation). The present study investigated whether vessel coarctation could be identified in patients with symptomatic renal artery stenosis (RAS). METHODS AND RESULTS: Consecutive symptomatic patients with angiographically proven atherosclerotic RAS who were referred for stent placement were studied by 30-MHz intravascular ultrasound before intervention (n=18) or after predilatation (n=18). Analysis included assessment of the media-bounded area and plaque area (PLA) at the most stenotic site and at a distal reference site (most distal cross-section in the main renal artery with normal appearance). Coarctation was considered present whenever the target/reference media-bounded area was

Accurate assessment of abdominal aortic aneurysm with intravascular ultrasound scanning: validation with computed tomographic angiography.

PURPOSE: The purpose of this study was to assess the accuracy of intravascular ultrasound (IVUS) parameters of abdominal aortic aneurysm, used for endovascular grafting, in comparison with computed tomographic angiography (CTA). METHODS: This study was designed as a descriptive study. Between March 1997 and March 1998, 16 patients with abdominal aortic aneurysms were studied with angiography, IVUS (12.5 MHz), and CTA. The length of the aneurysm and the length and lumen diameter of the proximal and distal neck obtained with IVUS were compared with the data obtained with CTA. The measurements with IVUS were repeated by a second observer to assess the reproducibility. Tomographic IVUS images were reconstructed into a longitudinal format. RESULTS: IVUS results identified 31 of 32 renal arteries and four of five accessory renal arteries. A comparison of the length measurements of the aneurysm and the proximal and distal neck obtained with IVUS and CTA revealed a correlation of 0.99 (P <.001), with a coefficient of variation of 9%. IVUS results tended to underestimate the length as compared with the CTA results (0.48 +/- 0.52 cm; P <.001). A comparison of the lumen diameter measurements of the proximal and distal neck derived from IVUS and CTA showed a correlation of 0.93 (P <.001), with a coefficient of variation of 9%. IVUS results tended to underestimate aneurysm neck diameter as compared with CTA results (0.68 +/- 1.76 mm; P =.006). Interobserver agreement of IVUS length and diameter measurements showed a good correlation (r = 1.0; P <.001), with coefficients of variation of 3% and 2%, respectively, and no significant differences (0.0 +/- 0.16 cm and 0.06 +/- 0.36 mm, respectively). The longitudinal IVUS images displayed the important vascular structures and improved the spatial insight in aneurysmal anatomy. CONCLUSION: Intravascular ultrasound scanning results provided accurate and reproducible measurements of abdominal aortic aneurysm. The longitudinal reconstruction of IVUS images provided additional knowledge on the anatomy of the aneurysm and its proximal and distal neck.

Inter-observer variability in the angiographic assessment of renal artery stenosis. DRASTIC study group. Dutch Renal Artery Stenosis Intervention Cooperative.

OBJECTIVE: To assess inter-observer agreement in the interpretation of renal angiograms. DESIGN: Comparison of the assessment of renal angiograms by three experienced radiologists, who evaluated the number of renal arteries and the presence, location, aspect and severity of a renal artery stenosis. SETTING: General hospital and university hospital serving urban and rural populations. PATIENTS: Patients with difficult-to-treat hypertension referred for diagnostic work-up; 312 angiograms with the intra-arterial digital subtraction technique were obtained from 289 consecutive patients. MAIN OUTCOME MEASURES: Inter-observer agreement was tested for the following parameters: number of arteries per kidney, presence of stenosis, location of stenosis (truncal, ostial), aspect of stenosis (concentric, eccentric, post-stenotic dilatation), severity of stenosis (reduction of lumen diameter in categories of 30%, 40%, etc. to 100%), and overall quality of the angiographic images. Kappa (kappa) values and weighted kappa between the three pairs of radiologists were used as estimates of inter-observer agreement RESULTS: Agreement about the number of renal arteries was reasonable (kappa = 0.50-0.72), as was agreement about the presence of stenosis (kappa = 0.68-0.86). Agreement about stenosis location and aspect was poor (kappa = 0.26-0.47 and kappa = 0.15-0.26, respectively). There was general agreement about the severity of stenosis (weighted kappa = 0.65-0.70), but it was not possible to distinguish between 50 and 60% stenosis or between 60 and 70% stenosis (kappa < 0.40). No correlation was found between agreement on severity of stenosis and the quality of the images. CONCLUSIONS: It is not realistic to make statements about what degree of renal artery stenosis is clinically significant, as long as the intra-arterial angiogram with digital subtraction remains the gold standard. It is likewise risky to rely too strongly on stenosis morphology as visualized by renal angiography in choosing between balloon angioplasty and stent deployment.

Three-dimensional ultrasound study of carotid arteries before and after endarterectomy; analysis of stenotic lesions and surgical impact on the vessel.

BACKGROUND AND PURPOSE: It has been proved that symptomatic patients with severe carotid stenosis benefit from endarterectomy. Currently used methods for quantitation of the severity of carotid stenosis have limitations, and the impact of endarterectomy on the operated region of carotid artery remains unknown. The purpose of this study was to examine the accuracy of a 3-D ultrasound system for quantitation of stenotic lesions and to evaluate changes in regional vessel volume and cross-sectional area after carotid endarterectomy. METHODS: We studied 14 patients with both carotid angiography and 3-D ultrasound. Of 13 patients who underwent surgery, 12 were reexamined with 3-D ultrasound after surgery. The length and volume of 20 randomly selected plaques were measured from 3-D data sets. The severity of stenosis was quantified by 3-D ultrasound using both a diameter method and an area method on cross-sectional views at the most stenotic site; the results were then compared with those from carotid angiography. The segmental vessel volume and average cross-sectional area of the operated artery both before and after endarterectomy were measured from 3-D ultrasound data. RESULTS: Good correlation was obtained between 3-D ultrasound and carotid angiography in quantitative analysis of carotid stenosis (SEE=12.4%, r=0.76, and mean difference=7.0+/-12.3% with the diameter method; SEE=10.5%, r=0.82, and mean difference=1.8+/-10.5% with the area method by 3-D ultrasound). 3-D ultrasound had excellent reproducibility and small intraobserver and interobserver variability in plaque length and volume measurements. No significant changes in segmental vessel volume and average cross-sectional area of the operated artery were observed after surgery in patients with suture closure. However, a significant increase in segmental vessel volume was obtained in patients with polyfluorethylene patches applied to the surgical opening of the artery. CONCLUSIONS: 3-D ultrasound can be used for both qualitative and quantitative analysis of plaques in the carotid artery and to detect and quantify significant carotid stenosis. Its volumetric potential has important clinical implications in serial follow-up studies for observing the progression or regression of stenotic lesions and for evaluating the outcome of interventional procedures such as endarterectomy or stent placement.

Residual arteriovenous fistulae after "closed" in situ bypass grafting: an overrated problem.

OBJECTIVES: To prospectively evaluate the incidence and consequences of residual arteriovenous (AV)-fistulae after "closed" in situ bypass grafting. METHODS: In 34 patients, 35 "closed" in situ bypasses were performed. Postoperative assessment of residual AV-fistulae and bypass patency was performed with duplex scanning. RESULTS: Postoperative mortality was 3%. During 35 "closed" in situ bypass procedures 216 side branches were coil embolised. Postoperatively 39 AV-fistulae were detected (15% of the total number of 216 + 39 = 255 side branches). Of these, 13 (5%) closed spontaneously. Fifteen (6%) remained unchanged and 11 (4%) were treated. In three patients four asymptomatic residual AV-fistulae were treated. In four patients seven symptomatic AV-fistulae were treated for: decreased distal bypass flow in one; persistent leg oedema in one; pain and redness of the skin in two. One-year primary patency was 80% (SE 8.4%). Residual AV-fistulae were detected in none of six bypass occlusions during follow-up. CONCLUSION: Residual AV-fistulae detected following "closed" in situ bypass grafting only need treatment if they are symptomatic, which is uncommon.