Analysis of the Common Femoral Artery and Vein: Anatomical Morphology, Vessel Relationship, and Factors Affecting Vessel Size.

Background and Objectives: We aimed to analyze the morphology of the common femoral artery (CFA) and common femoral vein (CFV) and the anatomical relationship between the two blood vessels, and to investigate the factors that influence the size of these blood vessels. Materials and Methods: This retrospective study included 584 patients who underwent abdominal and pelvic computed tomography from 1 February to 28 February 2021. We measured the vessels at three regions on both lower extremities (inguinal ligament, distal vessel bifurcation, midpoint) and analyzed and classified the degree of overlap between the CFA and CFV into three types, as well as the factors affecting vessel size. Results: After comparing the femoral vessels according to location, it was confirmed that the CFA and CFV were larger distally than proximally on both sides (p < 0.001). The degree of overlap increased distally (p < 0.001) but was less at the middle (p < 0.001) and distal (p = 0.011) regions on the right side. It was found that the size of CFA and CFV were related to age, sex, and body mass index (BMI) and that malignancy also affects the CFA size. Conclusions: The morphology of the CFA and CFV was conical and increased distally. The degree of overlap between the two blood vessels also increased distally but was less on the right than on the left. Age, sex, and BMI are significant factors affecting the sizes of the CFA and CFV, and malignancy is associated with the CFA size.

The transverse diameter of right common femoral vein by ultrasound in the supine position for predicting post-spinal hypotension during cesarean delivery.

BACKGROUND: Post-spinal anesthesia hypotension during cesarean delivery is caused by decreased systemic vascular resistance due to the blockage of the autonomic nerves, which is further worsened by inferior vena cava (IVC) compression by the gravid uterus. This study aimed to assess whether peak velocity and diameter of the IVC below the xiphoid or right common femoral vein (RCFV) in the inguinal region, as measured on ultrasound, could reflect the degree of IVC compression and further identify parturients at risk of post-spinal hypotension. METHODS: Fifty-six parturients who underwent elective cesarean section with spinal anesthesia were included in this study; peak velocities and anteroposterior diameters of the IVC and peak velocities and transverse diameters of the RCFV were measured using ultrasound before anesthesia. The primary outcome was the ultrasound measurements of IVC and RCFV acquired before spinal anesthesia and their association with post-spinal hypotension. Hypotension was defined as a drop in systolic arterial pressure by > 20% from the baseline. Multinomial logistic regression analysis was used to identify the association between the measurements of IVC, RCFV, and post-spinal hypotension during cesarean delivery. Receiver operating characteristic curves were used to test the abilities of the identified parameters to predict post-spinal hypotension; the areas under the curve and optimum cut-off values for the predictive parameters were calculated. RESULTS: A longer transverse diameter of the RCFV was associated with the occurrence of post-spinal hypotension (odds ratio = 2.022, 95% confidence interval [CI] 1.261-3.243). The area under the receiver operating characteristics curve for the prediction of post-spinal hypotension was 0.759 (95% CI 0.628-0.890, P = 0.001). A transverse diameter of > 12.2 mm of the RCFV could predict post-spinal hypotension during cesarean delivery. CONCLUSIONS: A longer transverse diameter of RCFV was associated with hypotension and could predict parturients at a major risk of hypotension before anesthesia. TRIAL REGISTRATION: This study was registered at http://www.chictr.org.cn on 16, May, 2018. No. ChiCTR1800016163 .

[Anatomy of foot perforator veins in surgery of varicose veins]. / Anatomiya perforantnykh ven stopy v khirurgii varikoznoi bolezni.

OBJECTIVE: To clarify the role of clinical anatomy of foot and ankle perforator veins (PV) in surgical treatment of varicose vein disease. MATERIAL AND METHODS: Anatomy of foot and ankle PV was assessed in 50 amputated lower extremities by anatomical dissection. RESULTS: There were 4-6 PVs at the medial surface of the foot. These veins connected medial marginal vein and vv. plantaris medialis (VPM). There were 2-3 PVs at the lateral surface of the foot. These veins connected lateral marginal vein and vv. plantaris lateralis (VPL). All PVs on the lateral surface of the foot constitute the neurovascular bundles. PVs flowing into vv. dorsalis pedis are localized on the medial surface of the medial marginal vein at the level of the ankle base. In most cases, we found an arterial branch nearby at the subfascial level. In anterior part of the plantar surface of the foot, we distinguished 4-5 small PVs (~1 mm) flowing into vv. digitales plantares through the commissural orifices of the aponeurosis. There were 6-9 vessels (~1 mm) along the fascial aponeurotic septa. These vessels connected superficial plantar venous network and plantar veins. Small arterial branch was found almost in all cases near these veins. Noteworthy is the area where the plantar veins lie on the quadratus plantae and are covered by a leaf of deep plantar fascia. This anatomy is similar to topography of posterior tibial veins. CONCLUSION: Foot perforator veins constitute the neurovascular bundles as a rule. Plantar vein topography and their relationship with PV confirm an existence of muscular-venous pump of the foot.

Anterior acetabular retractors and the femoral neurovascular bundle in anterior total hip arthroplasty: a cadaveric study.

PURPOSE: The direct anterior approach for primary total hip arthroplasty (THA) has become increasingly popular in recent years. Nerve compression or traction with a retractor is a common cause of nerve injury in this approach. The purpose of this cadaveric study was to evaluate the anatomic relationship of the femoral neurovascular bundle to the anterior acetabular retractor during direct anterior approach THA. METHODS: Eleven fresh-frozen cadavers underwent a standard direct anterior THA, with placement of an anterior acetabular retractor in the usual fashion between the iliopsoas and acetabulum for visualization during acetabular preparation. Careful dissection of the femoral triangle was performed, and the distances from the anterior retractor tip to the femoral nerve, artery, and vein were recorded and analyzed as mean distance ± standard deviation. RESULTS: In all 11 cadavers, the retractor tip was medial to the femoral nerve. The mean distance from retractor tip to femoral artery and vein was 5.9 mm (SD = 5.5, range 0-20) and 12.6 mm (SD 0.7, range 0-35), respectively. CONCLUSIONS: Surgeons should be aware of the proximity of the neurovascular structures in relation to the anterior acetabular retractor in the direct anterior approach, taking care to avoid perforating the iliopsoas muscle during retractor insertion and limit excessive traction to prevent nerve injury.

The angle range of leg abduction with external hip rotation which can minimize femoral artery and vein overlap in pediatric patients.

BACKGROUND: Since the femoral artery frequently overlaps the femoral vein, femoral central venous catheterization carries the risk of arterial puncture in pediatric patients. AIMS: We evaluated the angle range of leg abduction with external hip rotation to minimize the overlap between the femoral artery and vein in pediatric patients undergoing general anesthesia. METHODS: Eighty-two pediatric patients who underwent elective surgery with general anesthesia were enrolled in this study. Using ultrasonography, patients were divided into groups N (patients with non-overlap) and O (patients with continuing overlap) based on the presence of non-overlap range between the femoral artery and vein. The range minimizing the overlap was defined as the range without overlap in group N and as the range presenting the overlap that was less-than-half of the radius of the femoral vein in group O. By increasing the angle of leg abduction with external hip rotation, the starting and ending angles minimizing the overlap were found using ultrasonographic images. RESULTS: The angle range of leg abduction with external hip rotation minimizing the overlap between the femoral artery and vein was defined as the range from the maximum 99% confidence interval of starting angles to the minimum 99% confidence interval of ending angles, which was between 45° and 65° in group N and between 48° and 58° in group O, respectively. CONCLUSION: Positioning patients in a range of 48° and 58° leg abduction with external hip rotation can minimize the overlap between the femoral artery and vein. However, the clinical usefulness of this positioning for femoral venous catheterization remains to be seen.

Inter-arterial saphenofemoral junction: A rare anatomical variation.

Several anatomical variations involving the great saphenous vein have been described in the literature. Some of them concern the saphenofemoral junction, including duplication, ectasia, and different numbers of tributaries. In this case series, a rare, distinct variation, the inter-arterial saphenofemoral junction was reported.

Human Femoral Vein Diameter and Topography of Valves and Tributaries: A Post Mortem Analysis.

The femoral vein (FV) is a clinically important vessel. Failure of its valves can lead to chronic venous insufficiency (CVI) with severe manifestations such as painful ulcers. Although they are crucial for identifying suitable implant sites for therapeutic valves, studies on the topography of FV tributaries and valves are rare. Moreover, the femoral vein diameter (FVD) must be known to assess the morphometric requirements for valve implants. To reassess the anatomical requirements for valve implants, 155 FVs from 82 human corpses were examined. FVDs and tributary and valve topographies were assessed using a laboratory straightedge. The FVD increased from 6 mm in the distal femoropopliteal vein to 11 mm in the iliofemoral vein proximal to the saphenofemoral junction (SFJ). Diameters were significantly bigger in males than females. Height correlated positively with FVD. Distal to the SFJ, within a distance of 38 cm, one to eight valves were present. Up to two valves were present within 10 cm proximal to the SFJ. Individual tributary and valve topography must be considered to ensure appropriate design and successful implantation of a venous valve for CVI therapy in the FV. A suitable implant site would be proximal to the SFJ via an infrainguinal transfemoral access. Clin. Anat. 31:1065-1076, 2018. © 2018 Wiley Periodicals, Inc.

Anatomic variations of lower extremity venous system in varicose vein patients: demonstration by three-dimensional CT venography.

Background Understanding the anatomy of the lower extremity veins is essential for successful varicose vein treatment. Computed tomography (CT) venography may be used to obtain a comprehensive overview and detailed information regarding this. Purpose To describe anatomic variations of the lower extremity venous system in patients with varicose veins, using three-dimensional (3D) CT venography. Material and Methods A total of 810 limbs in 405 patients with suspected varicose veins were prospectively referred to undertake CT venography and included in our study population retrospectively. The CT venography images were evaluated by consensus of two cardiovascular radiologists. Anatomical variations of the lower extremity venous system and their incidence were analyzed. Specifically, the number of tributaries at saphenofemoral junction, relative location of the great saphenous vein (GSV) with respect to the common femoral artery bifurcation, pattern of saphenopopliteal junction, and end of thigh extension from the small saphenous vein (SSV) were assessed. Results The most frequent number of tributaries joining the GSV was four (44.4%, 360/810). Only 0.7% (6/810) of the limbs demonstrated unusual location of the GSV between the bifurcated superficial and deep femoral arteries. The most common pattern of veins at the saphenopopliteal junction was a larger caliber of saphenopopliteal junction than thigh extension from SSV (43.8%, 355/810), end of which joining the femoral vein directly (41.0%, 288/703). Conclusion CT venography with 3D reconstruction can be used to understand the anatomy of lower extremity veins and how their variations contribute to varicose veins.

[Changes in the Femoral Vein Diameter due to Lower Limb Flexion].

BACKGROUND: The purpose of this study was to in- vestigate the changes in the femoral vein (FV) diam- eter and the positional relationship during lower limb flexion using ultrasonography. METHODS: Twenty five male healthy volunteers were positioned in the supine and the hip joint was flexed to the target angles, followed by external rota- tion and abduction of the hip joint (hemi-frog-leg posi- tion). The flexion angle of the hip joint was mea- sured: before flexion (control), and at 30', 450, 60*, 75* flexion. The ultrasonograph transducer was held over the line which was 2 cm distal and parallel to the inguinal ligament Results: Compared with controls, the distance from the skin to the anterior wall of the FV was signifi- cantly shorter at 30 (15.1 mm vs 13.3 mm, P<0.01) and longer at 75" (15.1 mm vs 16.4 mm, P<0.03). The exposed width of the FV (length not overlapped by the femoral artery) was longest at 300(9.9 mm vs 12.1 mm, P<0.01). CONCLUSIONS: This study demonstrated that the hemi-frog-leg position was associated with significant increases in the diameter and exposed width of the FV. In particular, the most effective angle of the hip joint flexion was about 30*.

Three-dimensional reconstruction of the lower limb's venous system in human fetuses using the computer-assisted anatomical dissection (CAAD) technique.

OBJECTIVE: The aim of the present study was to show the feasibility and describe the first results of a 3D reconstruction of the venous network of the lower limbs in human fetus using the computer-assisted anatomical dissection (CAAD) technique. MATERIALS AND METHODS: We used limbs from two human fetuses, respectively, 14 and 15 weeks gestation old. Specimens were fixed in 10% formalin, embedded in paraffin wax and serially sectioned at 10 m. The histological slices were stained using HES and Masson Trichrome for soft tissues identification. Immunolabeling techniques using the Protein S-100 marker and the D2-40 marker were used to identify nerves and vessels, respectively. Stained slices were aligned manually, labeled and digitalized. The segmentation of all anatomical structures was achieved using the WinSurf(®) software after manual drawing. RESULTS: A 3D interactive vectorial model of the whole leg, including skin, bone, muscles, arteries, veins, and nerves was obtained. In all limbs, we observed the presence of a big axial vein traveling along the sciatic nerve. In addition, the femoral vein appeared as a small plexus. Although this is a common anatomical feature at the end of organogenesis, this feature is observed in only 9% of adults. Usually interpreted as an "anatomical variation of the femoral vein" it should be considered as a light truncular malformation. These observations bring further support to our proposed "angio-guiding nerves" hypothesis. CONCLUSION: This preliminary study shows that the CAAD technique provided an accurate 3D reconstruction of the fetal leg veins anatomy. It should bring a new insight for the understanding of the different steps of development of the human venous system.

Ultrasonographic anatomic variations of the major veins in paediatric patients.

BACKGROUND: The aim of our study was to describe the anatomic relationships in internal jugular (IJV), subclavian (SCV), and femoral (FV) vein sites. METHODS: One hundred and forty-two children had a two-dimensional (2D) ultrasound (US) evaluation of IJV, SCV, and FV sites. They were enrolled according to their age: 0-1 month old (n=9), 1 month old to 2 yr old (n=61), 2-6 yr old (n=22), 6-12 yr old (n=32), and 12-18 yr old (n=18). RESULTS: We found about 7.7% variation for the IJV. The most common anatomic variations were a lateral (nine children) or anterior (nine children) position of the IJV to the carotid artery. Regardless of the age category, about 9.8% of the anatomic variations were found for the FV. The most common anatomic variation in our study was that the FV ran anteromedially to the femoral artery (17 children). Anatomic variation of the SCV, regardless of age category, was about 7.4%. The most common anatomic variation was the SCV, which ran medially (10 children) to the subclavian artery. CONCLUSIONS: The relevant percentages of anatomic variations obtained for all these areas support at least a systematic US screening before attempting to obtain central venous access, ideally using a US-guided technique.

The effect of botulinum toxin B pretreatment to the blood flow in the microvascular anastomosis.

BACKGROUND: Although multiple factors can lead to free flap failure, vessel-related accidents are the most important. Many methods have been developed (both intraoperative and postoperative) to prevent vessel-related complications. In this article, we study the effects of a "preoperative treatment" using botulinum toxin B that could enhance the velocity and blood flow of vascular pedicles and decrease vascular accidents. METHODS: Ten Sprague-Dawley rats were pretreated with botulinum toxin type B at the perivascular area of the femoral vessel. Ten other rats were injected with saline as a control group. After 3 days, pedicle diameter and the peak mean frequency of blood in the pedicle were measured using laser Doppler flowmetry, and the peak mean blood velocity was calculated. We performed a "pedicle division and reanastomosis" operation to compare changes in vessel diameter and peak mean blood velocity. RESULTS: Vessel diameter was significantly increased in the botox-pretreated group for both veins and arteries. A comparison of the deep femoral vein and artery blood velocities showed that the peak mean velocity was significantly higher in the botox group. The average increase in blood velocity was significantly larger in the botox group. CONCLUSIONS: Botulinum toxin B is helpful by influencing the microvascular environment through an increase in the blood velocity of the pedicle.

Ultrasound investigation of leg position to enhance femoral vein exposure for cannulation.

BACKGROUND: Femoral venous access is an essential part of patient care in the emergency department (ED). However, current medical literature and texts have not dealt with it much using actual patient anatomy. OBJECTIVES: This study aimed to show that manipulation of the lower extremities may alter the anatomy to a more favorable position for cannulation. METHODS: Ultrasound examination was conducted on a prospective sample of ED patients to evaluate anatomical variance of the femoral artery and vein overlap as well as the change in femoral vein diameter with leg position. Bilateral measurements of the diameter of the vein were taken at three different leg positions (straight, abduction, and abduction with external rotation). RESULTS: This study enrolled a total of 132 ED patients. Of these, 122 (92%) patients showed some degree of overlap on the right and 126 (95%) patients showed some degree of overlap on the left. There was a statistically significant decrease in the percentage of overlap when moving the leg from a straightened position to an abducted position, and an additional decrease when moving the leg into an abducted and externally rotated position. There was also a statistically significant increase in the size of the femoral vein with each of these positions. CONCLUSIONS: Up to 95% of people have some degree of overlap of the femoral vein by the femoral artery. By positioning the leg in an abducted and externally rotated position, the amount of overlap is reduced and the diameter of the vein is increased, maximizing the percentage of the vein available for cannulation.

Anatomical examination of the great inguinal blood vessels in preterm and term neonates.

It is generally accepted that vessel cannulation is technically more difficult and results in more complications in neonates. A sound anatomical knowledge of the inguinal area is therefore important in the selection of appropriately sized central line catheters as well as the approach to central vessel access. Eleven stillborns were investigated. Birth weight (mean: 2,414 g, 900-4,100 g) and gestational age (mean 34 1/7 weeks', 27 6/7-42 1/7) varied within normal range. The outer diameters of the femoral artery (FA), femoral vein (FV), and great saphenous vein (GSV) were determined. The distance between the anterior superior iliac spine and the pubic tubercle was set as 100% and the vessel intersection points were calculated as percentage values of the inguinal ligament length, starting at the iliac spine. The FA has a diameter of 1.9 ± 0.5 mm without correlation to gestational age. The FA crosses the inguinal ligament centrally. The FV has a diameter of 3.1 ± 1.0 mm and does have correlation to gestational age. The FV crosses the inguinal ligament at 63-64%. The GSV has a diameter of 1.4 ± 0.7 mm. Its point of intersection at the level of the inguinal ligament is 68-70%. We conclude that cannulation of the femoral artery or vein should not be performed too far (<1 cm) from the inguinal ligament. The course of the GSV is not suitable for catheter insertion.

Redefining the surface anatomy of the saphenofemoral junction in vivo.

The surface anatomy of the saphenofemoral junction (SFJ) is especially relevant to surgeons. It is variably described in contemporary anatomy and clinical texts but is usually stated to lie 2.5-4 cm below and lateral to the pubic tubercle. The aim of this study was to map the SFJ accurately in healthy adults using ultrasound. One hundred healthy adults (mean age 27 years; 64 men) were scanned by an experienced sonographer using a 13-5 MHz linear probe. The center of the SFJ was recorded bilaterally in relation to the most superficial point of the pubic tubercle. The SFJ was readily identified in all participants. Its center was a mean of 2.4 ± 0.6 cm lateral (range 1-4.5 cm) and 1 ± 0.9 cm inferior to the pubic tubercle (range 2.5 above to 4 cm caudal to it). The junction was inferior to the pubic tubercle in 90% of lower limbs and at or above that level in 10%. In men, the SFJ was a mean of 2.6 cm lateral to the pubic tubercle and 1.2 cm inferior to it, compared with 2.2 and 0.6 cm, respectively, in women (P < 0.001). The SFJ was also slightly nearer the pubic tubercle in younger and thinner participants (P < 0.01). The center of the SFJ lies in a square extending 1-4 cm lateral and up to 3 cm below the pubic tubercle in >90% of adults. The junction is slightly closer to the pubic tubercle in women. These results provide a more robust guide to the surface anatomy of the normal SFJ.

Ultrasound-guided subclavian venous catheterisation - is this the way forward? A narrative review.

Central venous catheterisation is a commonly performed procedure in anaesthesia, critical care, acute and emergency medicine. Traditionally, subclavian venous catheterisation has been performed using the landmark technique and because of the complications associated with this technique, it is not commonly performed in the United Kingdom - where the accepted practice is ultrasound-guided internal jugular vein catheterisation. Subclavian vein catheterisation offers particular advantages over the internal jugular and femoral vein sites such as reduced rates of line-related sepsis, improved patient comfort and swifter access in trauma situations where the internal jugular vein may not be easily accessible. There is a growing body of evidence to suggest a potential emerging role for ultrasound-guided subclavian vein catheterisation. Barriers to this approach include many physicians still believing that the clavicle obscures imaging of the vein. In this article, we review the evidence supporting ultrasound-guided subclavian vein catheterisation and ask the question whether, in view of it potential advantages, it could be the way forward?

Left femoral vein is a better choice for cannulation in children: a computed tomography study.

BACKGROUND: Central venous catheters are often required in emergency rooms and intensive care and/or those undergoing major surgical procedures. In this study, we aimed to gain a better understanding of the anatomy of the femoral vessel in relation to central venous cannulation. METHODS: The right and left (total of 180) femoral veins (FVs) of 90 consecutive pediatric patients were retrospectively evaluated using computed tomography images. Patients were divided into two groups according to their age: group 1, patients up to 9 years of age; and group 2, patients between 9 and 16 years of age. RESULTS: The position and overlap of femoral artery (FA) to FV are significantly different between the left and right sides in both groups (P = 0.001). The left FV was most commonly located medial to the FA. However, the right FV was most commonly located posterior-medial to the FA. The incidence of overlap of the FA over the FV was significantly lower at the left side in both groups. CONCLUSION: The incidence of overlap of the FA over the FV was significantly lower at the left side in pediatric patients. This finding was similar between the patients aged 2-8 years and those aged 9-16 years and may have significant clinical implications. Guiding clinicians to select the left FV of children for cannulation may result in lower arterial puncture rates while accessing the central vein.

Anatomical and physiological changes in the venous system of lower limbs in pregnant women and findings associated with the symptomatology.

PURPOSE: Quantify the volume and diameter of veins in the lower limbs of primigravidae and associate the presence of venous signs and symptoms with the vascular measurements. METHODS: A cross-sectional study assessed 64 lower limbs of 32 healthy women of whom 16 were primigravidae between 22 and 36 weeks pregnant, and 16 nulligravidae. The women were submitted to physical assessment, air plethysmography and vascular ultrasound. The volumes and diameters of the main veins in the lower limbs were compared between pregnant and non-pregnant women. In the group of pregnant women, the attempt was also made to associate such measurements to the presence of vascular signs and symptoms. RESULTS: The average venous volume of the lower limbs (110.1 ± 30.2 and 94.7 ± 27.3 mL; p = 0.036), as well as the diameters of the common femoral (12.72 ± 2.27 and 10.14 ± 1.24 mm; p < 0.0001), saphenous (4.81 ± 1.15 and 3.55 ± 0.98 mm; p < 0.0001) and popliteal (6.87 ± 1.68 and 5.36 ± 1.07 mm; p < 0.0001) veins were, respectively, greater in the pregnant women compared with the control group. In pregnant women with venous stasis symptoms, a venous diameter of the saphenous vein compared to those without no symptoms (5.05 ± 1.19 and 4.09 ± 0.70 mm; p = 0.011) was noted. CONCLUSIONS: Anatomical and functional changes in the venous system during pregnancy were detected by the air plethysmography and the vascular ultrasound in primigravidae. In pregnant women, the presence of venous stasis symptoms found an anatomical and functional substrate detected in the differences in diameter of the saphenous vein.

An interconnected duplicated femoral vein and its clinical significance.

Anatomical variations in the femoral vein are of great clinical importance especially in cases of deep vein thrombosis (DVT). Knowledge of the variable anatomy of the femoral vein is important to minimise false-negative findings on ultrasound examination in patients with DVT and help to explain the 'silent' DVT. Furthermore, the presence of a duplicated femoral vein itself is associated with higher incidence of DVT. These venous anomalies are usually due to the truncular venous malformation. In the present study, while dissecting the right lower limb, we found a case of variation of the femoral vein. In this case, besides a duplicated femoral vein, we also noticed a 3rd interconnecting channel near the apex of the femoral triangle joining the two veins. This variation has not been reported previously by other authors. Considering its uniqueness and clinical importance, we decided to report this case.

Anatomic configuration affects the flow rate and diameter of porcine arteriovenous fistulae.

Although arteriovenous fistulae are currently the preferred form of vascular access, early failure is a significant problem. Since wall shear stress is thought to play an important role in the pathogenesis of early failure, and this stress varies markedly in different fistula configurations, we assessed the influence of configuration (curved or straight) on longitudinal changes of flow rate and lumen diameter in a porcine fistula model. Fistulae were created in eight pigs between the femoral artery and vein, with each animal having a curved and a straight configuration on opposite sides. Velocity measurements were obtained by ultrasound at the time of surgery and at intermediate time points up to 28 days. Quantification of both the configuration and the internal diameter of the fistulae was determined by CT scans. The overall rate of increased flow during each time interval (0 to 2 days, 2 to 7 days, and 7 to 28 days) was more pronounced with the curved fistulae. Moreover, the luminal diameter of curved fistulae had dilated more from the time of surgery to 28 days as compared to the straight fistulae. Thus, anatomical configuration of fistulae plays a major role in flow-mediated dilatation. Identifying the optimal configuration may result in increased diameter and consequently blood flow, and perhaps reduce the incidence of early failure.