Objectives. The beneficial effect of oral anticoagulants after infrainguinal venous bypass surgery is compromised by bleeding complications. We developed a model to identify patients, treated with anticoagulation, at risk of major haemorrhage and estimated whether this complication could have been prevented if patients had received aspirin.Design. Randomised clinical trial.Methods. Data of patients who participated in the Dutch Bypass Oral Anticoagulation or Aspirin Study were reanalysed using Cox regression. After infrainguinal bypass surgery these patients were randomised to oral anticoagulants (n = 1326) or aspirin (n = 1324).Results. Predictors of major haemorrhage for patients on oral anticoagulants were increased systolic blood pressure (>= 140 mmHg, hazard ratio [HR] 1.62), age >= i75years (HR 2.77) and diabetes mellitus (HR 1.60). If the 345 patients in the highest risk quartile had received aspirin, major haemorrhages would have been reduced from 46 to 22, with no major changes in ischemic events and graft occlusions. In the subgroup with venous bypasses major haemorrhages would have been reduced from 27 to 13, at the cost of seven more ischemic events (mostly fatal) and 17 more graft occlusions.Conclusions. Treating patients at highest risk of major haemorrhage with aspirin instead of oral anticoagulants would have resulted in a reduction of non-fatal haemorrhages, but for venous bypasses this reduction was outweighed by an increase in ischemic events and graft occlusions. We still recommend treatment with oral anticoagulants after peripheral venous bypass surgery.

Objective: Patch closure after carotid endarterectomy (CEA) improves clinical outcome compared with primary closure. Whether there are differences in outcome between various patch materials is still not clear. The objective of this retrospective study was to investigate whether a relationship exists between the patch type and the number of microemboli as registered during CEA by transcranial Doppler imaging, the clinical outcome (transient ischemic attack and cerebrovascular accident), and the occurrence of restenosis.Methods, We included 319 patients who underwent CEA. Intraoperative microembolus registration was performed in 205 procedures. Nicroembolization was recorded during four different periods: dissection, shunting, clamp release, and wound closure. The decision to perform primary closure or to use a patch for the closure of the arteriotomy was made by the surgeon, and Dacron patches were used when venous material was insufficient. Cerebral events were recorded within the first month after CEA, and duplex scanning was performed at 3 months (n = 319) and 1 year (n = 166) after CEA. A diameter reduction of more than 70% was defined as restenosis.Results. Primary, venous, and Dacron patch closures were performed in 83 (26.0%), 171 (53.6%), and 65 (20.4%) patients, respectively. Primary closure was significantly related to sex (Dacron patch, 35 men and 30 women; venous patch, 108 men and 63 women; primary closure, 72 men and I I women; P < .00 1). The occurrence of microemboli during wound closure was also related to sex (women, 2.5 +/- 0.6; men, 1.0 +/- 0.2; P = .0 1). Additionally, during clamp release, Dacron patches were associated with significantly more microemboli than venous patches (11.1 +/- 3.4 vs 4.0 +/- 0.9; P < .01), and this difference was also noted during wound closure (3.1 +/- 0.9 vs 1.4 +/- 0.4; P < .05). Transient ischemic attacks and minor strokes after CEA occurred in 5 (2.4%) of 205 and 6 (2.9%) of 205 procedures, respectively, and the degree of microembolization during dissection was related to adverse cerebral events (P = .003). In contrast, the type of closure was not related to immediate clinical adverse events. However, primary closure and Dacron patches were associated with an increase in the restenosis rate compared with venous patches: after 400 days, the restenosis rate for Primary closure was 11%, Dacron patch 16%, and venous patch 7% (P = .05; Kaplan-Meier estimates).Conclusions. Microemboli are more prevalent during clamp releases and wound closure when Dacron patches are used. Additionally, the observed differences in embolization noted by patch type were mainly evident in women. However, the use of Dacron patches was not related to immediate ischemic cerebral events but was associated with a higher restenosis rate compared with venous patch closure. This suggests that venous patch closure may be preferred for CEA. (J Vasc Surg 2005).

Objective. To compare the consequences of occlusion of infrainguinal venous and prosthetic grafts.Methods. In total, 2690 patients were included in the Dutch BOA study, a multicenter randomised trial that compared the effectiveness of oral anticoagulants with aspirin in the prevention of infrainguinal bypass graft occlusion. Two thousand four hundred and four patients received a femoropopliteal or femorodistal bypass with a venous (64%) or prosthetic (36%) graft. The incidence of occlusion and amputation was calculated according to graft material and the incidence of amputation after occlusion was compared with Cox regression to adjust for differences in prognostic factors.Results. The indication for operation was claudication in 51%, rest pain in 20% and tissue loss in 28% of patients. The mean follow up was 21 months. After venous bypass grafting 171 (15%) femoropopliteal and 96 (24%) femorodistal grafts occluded. After prosthetic bypass grafting 234 (30%) femoropopliteal and 25 (38%) femorodistal grafts occluded. Patients with occlusions in the venous group had more severe ischemia, less runoff vessels and were older than the patients with prosthetic grafts. In the venous occlusion group 54 (20%) amputations were performed compared to 42 (16%) in the prosthetic occlusion group; crude hazard ratio 1.17 (95% Cl 0.78-1.75). After adjustment for above mentioned differences in patient characteristics the hazard ratio was 0.86 (95% Cl 0.56-1.32).Conclusion. The need for amputation after occlusion is not influenced by graft material in infrainguinal bypass surgery.

AIM: Seeding venous endothelial cells (EC) onto damaged vascular surfaces attenuates the development of intimal hyperplasia. Unlike venous EC, fat derived microvascular endothelial cells (MVEC) do not require a culture step to increase the yield. The authors investigated whether fat derived MVEC are suitable to reduce intimal hyperplasia after PTA. METHODS: Five rabbits were subjected to percutaneous transluminal angioplasty (PTA) of both iliac arteries. One side was seeded transluminally with autologous perirenal fat derived MVEC, using a double balloon catheter. The contralateral side was sham seeded, and served as a control. Follow-up was 4 weeks. Another rabbit was used for a feasibility experiment. This rabbit was subjected to a 1-sided seeding procedure and was sacrificed after 1 week. In a 7th rabbit, a 1-sided PTA was transformed, and autologous labelled cells were injected in the distal aorta instead of seeded, follow-up was 1 week. Histological investigation was per-formed. RESULTS: The MVEC seeded artery of the pilot experiment was patent. All sham seeded arteries (5) except for 1 were patent. The patent ones showed moderate intimal hyperplasia. MVEC seeding (5) resulted in occlusion twice. In the patent MVEC seeded arteries intimal hyperplasia was present in more extended form than in the sham seeded arteries. Both the patent MVEC- and sham-seeded arteries were covered with an EC layer. Injected labelled MVEC were not found again on the de-endothelialized artery. CONCLUSION: In this study seeding of fat derived MVEC on damaged native arteries results in an increased development of intimal hyperplasia and a decreased patency. One of the reasons may be the presence of non-EC in the seeded cell population.

BACKGROUND:Microvascular endothelial cells (MVEC) derived from s.c. fat are seeded on vascular grafts to prevent early occlusion. We have demonstrated the presence of contaminating cells contributing to MVEC seeding-related intimal hyperplasia in MVEC isolates from fat tissue. We found that cell isolates additionally purified after the isolation process, were associated with a reduced thrombogenicity and development of intimal hyperplasia in vitro. A combination of 11Fibrau (F11)- and CD14-coated Dynabeads was used to deplete the contaminating cells, fibroblasts, and monocytes/macrophages. Unfortunately, clinical-grade F11 is not available, and thus cannot be used for clinical practice. CD34 selection with clinical-grade products is widely used for the isolation of hematopoietic progenitors, and endothelial cells (EC) express CD34 on their surfaces. The aims of this study were to test the effectiveness of two different CD34-selection techniques for purification of MVEC, and to compare the results with those of the F11/CD14-method.METHODS:Liposuction fat was enzymatically digested and centrifuged twice to remove adipocytes and collagenase. CD34 selection was performed using the commercially available methods from Nexell or Miltenyi. Both techniques were modified for our use. The purity after isolation and culture, and recovery were determined by flow-cytometry (CD31-expression) and compared with that of cells purified with the F11/CD14-method.RESULTS:Besides MVEC, the contaminating fibroblasts and macrophages/monocytes weakly expressed the CD34 Ag. Enrichment of MVEC was not successful with the Miltenyi method. Variations in neither the dose of Ab nor the use of direct selection and different separation programs improved the results. With the Nexell method, MVEC were enriched to 86%, a comparable purity to that obtained with the F11/CD14-method. However, a lower recovery was achieved with the Nexell method.CONCLUSION:Enrichment of MVEC could be achieved with a modified protocol of the clinical grade CD34(+) selection method from Nexell, but not with the CD34 method from Miltenyi.

OBJECTIVE:Tracing and treating cardiovascular risk factors in patients with arterial vascular disease and in patients with high risk of developing vascular diseases.DESIGN:Descriptive.METHOD:In September 1996 at the University Medical Center Utrecht, the Netherlands, a vascular screening and prevention programme was started for newly referred patients aged between 18 and 79 years presenting with one or more of the following: coronary artery disease, cerebrovascular disease, peripheral arterial disease, hypertension, diabetes mellitus or lipid disorders. In all patients, risk factors for developing (new) vascular diseases were assessed and non-invasive vascular diagnostics aimed at finding asymptomatic vascular disease were done.RESULTS:Between 1 September 1996 and 31 October 2002, 3075 patients took part in the screening programme. Within the various patient groups and often despite treatment, there was a high prevalence of hypertension, smoking, dyslipidaemia, hyperhomocystemia and overweight. In patients with peripheral artery disease, carotid artery stenosis > or = 50% was detected in 17% and an aneurysm of the abdominal aorta in 5%. In patients presenting with diabetes mellitus, hypertension or lipid disorders the prevalence of asymptomatic arterial disease was 1-5%. Asymptomatic vaso-dilatory disease in particular was uncommon.CONCLUSION:A hospital-wide vascular screening and prevention programme for a wide range of high-risk vascular patients was shown to be feasible and resulted in the detection of risk factors and asymptomatic arterial disease. It is a reliable starting point for actual risk intervention. More attention should be paid to treating existing risk factors.

PURPOSE:To assess the value of MR angiography (MRA) with automatic table movement in a consecutive series of patients with peripheral arterial disease.METHODS:Seventy-two patients underwent both conventional angiography (CA) and MRA for peripheral arterial occlusive disease. Both techniques were scored in a masked way. Consensus scoring for CA was compared with MRA scoring per observer. If there was a discrepancy in scoring of a segment on MRA and CA, the images were reviewed and a consensus arrived at.RESULTS:Observer A found 7.4% and observer B found 6.5% of the segments could not be analyzed on MRA. Observer A scored 11.4% dissimilar on MRA and CA, observer B 15.2%. In the aortoiliac arteries, this was mainly caused by stents and overestimation of stenoses; in the crural arteries it resulted from underestimation of the stenoses on MRA. Overall sensitivity and specificity for the aortoiliac, femoropopliteal and crural vessels were respectively 90% and 91%, 90% and 96%, 59% and 96% for observer A, and 85% and 91%, 84% and 89%, 68% and 85% for observer B.CONCLUSION:Although MRA of the lower extremities is a promising technique, improvements still need to be made. In particular, MRA below the knee is suboptimal for clinical use.

PURPOSE: To assess accuracy of contrast material-enhanced magnetic resonance (MR) angiography as compared with three-dimensional (3D) time-of-flight (TOF) MR angiography and reference digital subtraction angiography (DSA) in diagnosis of carotid artery stenosis.MATERIALS AND METHODS: Enhanced and 3D TOF MR angiography and DSA were performed in 51 consecutive patients suspected of having carotid artery stenosis at duplex ultrasonography. Stenoses were measured by two independent observers blinded to clinical information and other test results. Pearson correlation coefficients were used, and K for interobserver variabilities was estimated. Sensitivity and specificity of enhanced and 3D TOF MR angiography were calculated and compared with those of DSA.RESULTS: Pearson correlation coefficients were 0.94 (P < .01) for enhanced angiography versus DSA, 0.92 (P < .01) for 3D TOF angiography versus DSA, and 0.93 (P < .01) for enhanced versus 3D TOF angiography for observer 1 and 0.94 (P < .01), 0.95 (P < .01), and 0.94 (P < .01), respectively, for observer 2. K statistics were 0.81 for enhanced angiography, 0.79 for 3D TOF angiography, and 0.78 for DSA. Stenosis measurements of observer 1 at enhanced MR angiography, with inclusion of carotid arteries on the symptomatic side only, compared with those of DSA yielded a sensitivity of 90% (95% CI: 68%, 99%) and a specificity of 77% (95% CI: 55%, 92%). 3D TOF angiography yielded a sensitivity of 86% (95% CI: 67%, 97%) and a specificity of 73% (95% CI: 50%, 89%) compared with those of DSA. For observer 2, sensitivity and specificity for enhanced angiography were 91% (95% CI: 70%, 99%) and 76% (95% CI: 52%, 91%), respectively, and 90% (95% CI: 68%, 99%) and 77% (95% CI: 51%, 92%), respectively, for 3D TOF angiography.CONCLUSION: Accuracy of enhanced MR angiography in diagnosis of severe stenosis is similar to that of 3D TOF MR angiography. (C) RSNA, 2003.

Background and Purpose— In patients with severe obstruction of the internal carotid artery (ICA), it is recognized that the preoperative failure to visualize collaterals of the circle of Willis increases the risk of hemispheric ischemia before, during, and after carotid endarterectomy (CEA). The purpose of the present study was to assess the effect of CEA on the anatomy and function of the circle of Willis. Methods— Time-of-flight and phase-contrast MR angiography were used to study changes in vessel diameter and collateral flow of the circle of Willis in 48 patients with 70% to 99% ICA stenosis before and after CEA. Results— In patients with unilateral ICA stenosis, all preoperative vessel diameters on both sides of the circle of Willis were larger than in control subjects. All demonstrated a significant diameter decrease to reach normal values after CEA. Furthermore, preoperative collateral flow patterns normalized after CEA ( P =0.03). In patients with stenosis and contralateral ICA occlusion, CEA resulted in a significant increase in the prevalence of collateral flow via the anterior communicating artery (33% to 83%, P <0.01) and a significant increase in diameter of both A1 segments ( P <0.05) in patients in whom collateral flow developed after CEA. Conclusions— CEA reduces the caliber of compensatory collateral channels to normal levels by MR angiography measurements in the presence of severe unilateral stenosis; when the opposite side is occluded and the stenosis is removed ipsilaterally, a greater amount of compensatory collateral circulation can be measured on both the occluded side and the fully opened side.

Objective: The purpose of this study was to investigate whether screening for internal carotid artery stenosis (ICAS) and aneurysm of the abdominal aorta (AAA) is indicated in patients with either manifest atherosclerotic disease or with only risk factors for atherosclerosis.Study design: Data were obtained for 2274 patients enrolled in the SMART study, an ongoing single-center, prospective cohort study of patients referred to our vascular center with manifest atherosclerotic disease (peripheral atherosclerotic disease [PAD]; transient ischemic attack [TIA], stroke, or ICAS; AAA; angina pectoris; or myocardial infarction [MI]) or with only risk factors for atherosclerosis (diabetes mellitus, hypertension, hypertipidemia). The presence of ICAS or AAA was determined with duplex scanning and ultrasonography.Results. The prevalence of ICAS 70% or greater is low in patients with risk factors for atherosclerosis only (1.8%-2.3%), intermediate in patients with angina pectoris or MI (3.1%), and highest in patients with PAD (12.5%) or AAA (8.8%). The prevalence of AAA 3 cm or larger is low in patients with risk factors for atherosclerosis only (0.4-1.6%), intermediate in patients with angina pectoris or MI (2.6%), and highest in patients with PAD (6.5%) or TIA, stroke, or ICAS (6.5%). The prevalence of AAA larger than 5 cm is low in all of the considered patient groups. The yield of screening can be optimized through selection on the basis of simple patient characteristics. In patients with PAD, selecting those with advanced age (> 54 years) increased the prevalence of WAS to 21.8%. Selecting patients with lower diastolic blood pressure (< 83 mm Hg) increased the prevalence of WAS to 17.9%. In patients with both advanced age and lower diastolic blood pressure, the prevalence of ICAS increased to 34.7%. Selecting patients with advanced age increased the prevalence of AAA 3 cm or larger to 9.6%. In patients with TIA, stroke, or ICAS, selecting those with advanced age increased the prevalence of AAA 3 cm or larger to 8.2%. Selecting patients with taller stature (> 169 cm) increased the prevalence of AAA 3 cm or larger to 9.3%. In patients with advanced age and taller stature, the prevalence of AAA 3 cm or larger increased to 13.1%.Conclusions. Screening for ICAS should be limited to patients referred with PAD or AAA, especially those with advanced age or with low diastolic blood pressure. Screening for AAA should be limited to patients referred with PAD or with TIA, stroke, or ICAS, particularly those with advanced age or tall stature. In patients referred with angina pectoris or MI and those referred with only risk factors for atherosclerosis, screening cannot be endorsed. (J Vasc Surg 2003;37:1226-33.).

BACKGROUND AND PURPOSE:Time-of-flight (TOF) magnetic resonance angiography (MRA) is commonly used to visualize the carotid arteries; however, flow void artifacts can appear. Our purpose was to determine the frequency and diagnostic meaning of flow voids by using real patient data, as part of a larger study of MRA compared with the criterion standard, digital subtraction angiography (DSA).METHODS:In 1997-2000, 390 consecutive patients with sonographic findings suggestive of carotid artery stenosis were included in this study. All patients subsequently underwent three-dimensional (3D) TOF MRA and conventional DSA. The frequency of flow void artifacts on 3D TOF MRA images were compared with stenosis measurements on DSA images.RESULTS:We recorded 107 flow voids (16%) during 3D TOF MRA of 662 carotid arteries. DSA images were available for comparison in 102 cases. The median percentage of stenosis in this subgroup of flow voids on MRA images was 80%, compared with measurements on DSA images according to the North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria. Stenoses ranged from 36% to 100% (occlusion). Three flow voids (2.9%) were in the 0-49% range; 11 (10.8%), in the 50-69% range; and 86 (84.3%), in the 70-99% range. Two flow voids (2.0%) represented occlusions. The positive predictive value of a flow void artifact for the presence of severe (70-99%) stenosis was 84.3% (95% CI: 77.3%, 91.4%).CONCLUSION:Flow void artifacts represented severe stenosis in most of the arteries. According to our data, the assumption that flow voids on 3D TOF MRA images represent severe stenosis is justified.

Objective. The purpose of this study was to determine the optimal intensity of oral anticoagulants in patients who participated in a randomised trial of oral anticoagulants or aspirin after infrainguinal bypass graft surgery. Design. Planned secondary data analysis. Method. The distribution of the time spent in the therapeutic target area, distributed in international normalized ratio (INR) classes of 0.5 INR units, was calculated assuming a linear change between successive measurements. INR-specific incidence rates of ischaemic and haemorrhagic events were calculated as the ratio of the number of events in the different INR classes and the total patient-time spent in the classes concerned. The relationship between INR classes and the incidence of events was calculated with a Poisson regression model. The intensity of anticoagulation and the incidence of haemorrhages were also calculated for various age categories. Results. A total of 41,928 INR measurements were recorded in 1326 patients (mean age: 69 years; 65% men) over a period of 1698 patient-years. Patients spent 50% of the total time within the target range of 3.0 to 4.4 INR. Most of the patient time (60%) was spent between 2.5 and 3.9 INR. For each increasing class of 0.5 INR, the incidence of ischaemic events (n = 154, INR data on event available in 49% of cases) decreased by a factor of 0.97 (95%-CI: 0.87-1.08). The incidence of major haemorrhages (n = 123, INR data on event available in 65% of cases) increased significantly by a factor of 1.27 (95%-CI: 1.19-1.34) for each increasing 0.5 INR class. The optimal target range was 3.0 to 3.9 INR, with an incidence of 3.8 events (0.9 ischaemic and 2.9 haemorrhagic) per I00 patient-years. The proportion of patient-years spent within the target range increased somewhat with age, while the incidence of haemorrhages increased as well. Conclusion. The target range of 3.0 to 3.9 INR was the optimal range of anticoagulation intensity achieved and was safe for preventing ischaemic events in patients after infrainguinal bypass graft surgery. Although age did not affect the accuracy of anticoagulation intensity, the risk of bleeding complications did increase with age.

OBJECTIVE:Hyperhomocysteinemia has been identified as a risk factor for (cardio)vascular disease. Whether hyperhomocysteinemia contributes to graft failure after peripheral bypass surgery remains unclear. The present study evaluated the influence of hyperhomocysteinemia on graft patency after infrainguinal bypass surgery.DESIGN:The present study was designed as a nested case-control study.METHOD:In this study (nested in the Dutch Bypass Oral anticoagulants or Aspirin Study), 150 patients with graft occlusion were each matched with two randomly selected controls with patent grafts (N = 299) from the same trial. Venous blood samples were drawn from cases and controls, and total plasma homocysteine (tHcy) was determined. Mean serum homocysteine levels and the presence of hyperhomocysteinemia (>95th percentile in healthy individuals) were compared between cases and controls.RESULTS:No significant differences were found between serum levels of homocysteine in patients with and without graft occlusion. The mean plasma homocysteine levels were 14.4 micromol/L and 14.9 micromol/L in the case and control groups, respectively. The resulting mean difference was -0.4 (95% confidence interval [CI], -1.8-0.9). The odds ratio of hyperhomocysteinemia was 0.81 (95% CI, 0.49-1.33). Adjustment for risk factors of graft occlusion did not change these results.CONCLUSIONS:Postoperative raised serum levels of homocysteine proved not to be a risk factor for graft occlusion after infrainguinal bypass grafting.

The Dutch Society for Vascular Surgery was founded in 1981, as the first daughter of the Association of Surgeons in the Netherlands. Twenty years of vascular surgery show a broad perspective. Aside from the traditional handywork--central vascular reconstruction, bypass surgery (especially in the legs), and carotid surgery--, there have been many developments. Operations are less invasive and vascular surgeons are cooperating more and more intensively with other medical disciplines, especially radiology. Examples are the endovascular treatment of abdominal aortic aneurysm, in which an endoprosthesis is inserted via minute incisions in the groin by the vascular surgeon and an (interventional) radiologist together. In addition, interventions such as percutaneous transluminal angioplasty and stenting as well as new diagnostic possibilities (e.g. MRA) strengthen the cooperation with the radiologists. The multidisciplinary approach is also extremely important in other areas. Vascular surgeons team up with internal-medicine specialists (diabetes, hypertension, lipid metabolism disorders, thrombotic syndromes, etc.), rehabilitation specialists and podotherapists (in cases of diabetic foot and amputation), vascular laboratory technicians (diagnostics and follow-up by means of doppler and duplex techniques), and neurologists (cerebrovascular diseases). In the vascular centres, patients are treated effectively by a multidisciplinary team that draws up a plan for diagnosis and treatment. The two-year postgraduate course in vascular surgery is one of the tools used to guarantee and improve the high standard of quality. To this end, cooperation within Europe in the European Society for Vascular Surgery and the development and organisation of European examinations in vascular surgery are also of the essence.

OBJECTIVE In patients with stenosis of the internal carotid artery (ICA), the presence of collateral circulatory pathways may be crucial to maintain cerebral perfusion pressure, metabolism, and function. The purpose of the present study was to determine whether patients with asymptomatic stenosis of the ICA have a better collateral ability of the circle of Willis when compared with patients with symptomatic ICA stenosis. METHOD Magnetic resonance angiography consisting of the circle of Willis was performed in 19 patients with severe asymptomatic ICA stenosis and in 21 patients with severe symptomatic ICA stenosis prior to carotid endarterectomy and in 53 control subjects. Between group comparisons were made for function (directional flow) and anatomy (diameter). RESULTS In patients with asymptomatic ICA stenosis, the prevalence of collateral flow via the anterior communicating artery was significantly increased (37%, 7 of 19) compared with symptomatic patients (10%, 2 of 21) and control subjects (0%; P <.001). Patients with asymptomatic ICA stenosis demonstrated the largest mean diameter of the anterior communicating artery (1.33 +/- 0.18 mm) compared with patients with symptomatic ICA stenosis (1.22 +/- 0.18 mm) and control subjects (1.06 +/- 0.10 mm, P <.05). No differences in collateral flow pattern or diameter were found for the posterior communicating artery between the groups. CONCLUSIONS The present cross-sectional study demonstrates the importance of an adequate hemodynamic compensation via the circle of Willis in patients with ICA stenosis. Whether differences in collateral compensation can be used to select patients for CEA has yet to be determined.

BACKGROUND:Endurance athletes often have restrictions in flow in their iliac arteries during exercise. Such restrictions have previously been ascribed solely to intravascular lesions. We postulate that flow could also be restricted by functional kinking in the arteries, and that surgical release of these kinks might be an effective treatment.METHODS:We prospectively studied 80 endurance athletes who had complaints suggestive of flow restriction in the iliac arteries of one (n=74) or both (6) legs (total 92 legs). Using vascular diagnostic tools, we examined athletes while they were doing activities that often provoke flow restrictions. Restrictions were determined by measurement of systolic pressure in the ankle after exercise; peak systolic velocities were measured with echo-doppler. Kinks were detected with echo-doppler and magnetic-resonance angiography. When functional kinking was diagnosed as the cause of the restriction, the athlete was offered surgery to release the iliac arteries, as part of our prospective study.FINDINGS:We recorded flow restrictions in the iliac arteries of 58 of 92 (63%) legs. In 40 of these legs (69%), kinks were the most important cause of the restriction, making these legs suitable for surgical release. We operated on 23 of 58 (40%) legs. All athletes who had an operation subjectively improved. Maximum workload in a cycling test and ankle pressure significantly improved after the operation. 20 (87%) athletes were able to successfully return to their desired high level of competition.INTERPRETATION:Our sports-specific protocol is effective in detecting kinking of the iliac arteries as a cause for flow restriction in athletes who have few intravascular abnormalities when investigated with conventional vascular diagnostic tools. Surgical treatment directed at the kinking was less invasive and therefore a better alternative to vascular reconstruction in these athletes.