True aneurysm in autologous hemodialysis fistulae: definitions, classification and indications for treatment

Introduction

The creation of an autologous arteriovenous access (AVA) is a frequent surgical procedure in patients with end-stage kidney disease (1). While the creation of the AVA belongs to core vascular surgery, the primary patency rate at five years is only 40-50% and the need for re-intervention is high (2). In contrast to other clearly described AVA complications, aneurysm formation is still poorly described in recent literature. In studies of hemodialysis patients the frequency of aneurysm formation varies considerably between 6% and 60% (3, 4). Also, the indication for the treatment and type of intervention varies among the authors. This heterogeneity results from the insufficient current international guidelines (K/DOQI-Kidney Disease Outcomes Quality Initiative, SVS-Society of Vascular Surgery North-America, VAS-Vascular Access Society) (1, 5, 6) regarding the AVA aneurysm. The objectives of the present paper are to close this information gap: definition, mechanism of development, classification, indications and type for treatment of AVA aneurysm, based on an extensive review of the literature.

Materials and methods

Even if this review does not meet all the criteria of the PRISMA statement (7) for systematic reviews, the main recommendations for a search of the literature were followed for the purpose of the present review.

Literature search

A literature search was performed of the articles published between April 1, 1967, and March 1, 2014. The databases searched included Medline (via PubMed) and the Cochrane Database of Systematic Reviews. Articles with the descriptor “Aneurysm” AND “Arteriovenous” AND “Hemodialysis” with a prior checking in the MeSH database including synonyms were searched. All sub-headings were included in the searches. After identifying suggested titles, the corresponding abstracts were read online to select articles for printing and for further analysis. Reference lists from the included publications and relevant literature reviews were also examined. All literature reviews were done by the principal author.

Eligibility criteria

Only publications in English were included. For inclusion in this review, studies needed to have assessed the association of true aneurysm with autologous AV hemodialysis access. Papers focusing only on prosthetic AV access were excluded. Papers reporting a mix of aneurysm and pseudoaneurysm of autologous and prosthetic AV access were carefully analyzed and data regarding autologous AV access were used for the review.

Study selection

From a total of 327 papers, 54 non-English papers, 40 case reports and 167 papers which did not meet the eligibility criteria were removed. The remaining 66 papers were reviewed.

Definition of AVA aneurysm

The Society for Vascular Surgery defines a true aneurysm as a circumscribed dilatation of all three vessel layers in contrast to a pseudoaneurysm which represents a focal dilatation of the vessel wall by neointimal and fibrous tissue (5). Autologous AVA can be complicated by both aneurysm and pseudoaneurysm formation (5). In the current K/DOQI guidelines an aneurysm is defined as an abnormal blood-filled dilation of the blood vessel wall, resulting from disease of the vessel wall, and pseudoaneurysm is a vascular abnormality that resembles aneurysm but the outpouching is not limited by a true vessel wall, but rather by an external fibrous tissue (1). In the current guidelines of the Vascular Access Society, a recommendation regarding aneurysm and pseudoaneurysm is lacking (6). An interesting expert definition was proposed by Vesely (8) who recommended using the term aneurysm for the autologous AVA only when the etiological factor is showing increased intraluminal pressure due to distal stenosis, and Vesely goes on to recommend using the term pseudoaneurysm when etiology was due to a degeneration of the vein wall, from repeated cannulation trauma. Even if this definition seems logical, it is difficult to use in clinical practice, since often both etiological factors are present.

Basing the definition of AVA aneurysm on size is controversial, and there is no precise size criterion in the current guidelines. While the diameter of the aneurysm is a criterion for treatment of arterial aneurysms, it is not necessarily a criterion for the treatment of access aneurysms that develop in AVA.

Most previous published reports defined an AVA aneurysm based upon size (Tab. I). The definition can be subjective such as two to three times larger than the diameter of the normal vein, or objective such as a diameter larger than 20 mm. However, management of an AVA aneurysm is determined by clinical signs and symptoms, not a specific size.

TABLE I -

Retrospective studies which describe the treatment of AVA aneurysm (as-assisted primary patency, °studies including also prosthetic AVA)

Author	Year published	No pts with AVA aneurysm of native access	Size criterion of aneurysm	Aneurysm diameter (mm)	Forearm location	Upper arm location	Treatment techniques	Patency/FU
AVA = arteriovenous access; PTFE = polytetrafluoroethylene.
Rokosny et al (34)	2014	62	3× larger diameter than other venous segments from the access site	34.47 ± 7.33	40	22	Aneurysmorrhaphy with PTFE mesh	79% (12 m)
Hossny (46)	2013	14	-	53 ± 16	5	9	Partial aneurysmectomy	86% (12 m)
Zink et al (47)	2013	17	2× greater diameter than remainder of access	-	-	-	Stent grafting	47% (6 m)
Kinning et al (48)	2013	4	-	-	0	4	Stent grafting	54% (6 m) as.
Belli et al (49)	2012	26	-	26 ± 9.3	11	15	Excision and aneurysm repair with vein/prosthesis or primary suture Ligation with or without excision	52% (12 m)
Almehmi and Wang (38)	2012	36	-	-	10	26	Partial aneurysmectomy	56% (6 m)
Shah et al (50)	2012	11	-	19.5	-	-	Stent grafting	69% (6 m)
Bachleda et al (51)	2011	6	-	-	-	-	Partial aneurysmectomy	-
Ekim et al (52)	2011	20	-	55.2 ± 17.3	2	18	Plication/excision	-
Pasklinsky et al (19)	2011	23	3× larger diameter than autologous vessel/more than 20 mm	33	10	13	Excision and aneurysm repair with vein/prosthesis Ligation with or without excision	47% (12 m)
Shemesh et al (17)	2011	11	-	30 ± 9	1	10	Stent grafting	87% (12 m)
Karatepe et al (53)	2011	28	more than 40 mm	40	21	7	Plication Excision and aneurysm repair with vein/prosthesis Stent grafting	100% (6 m)
Berard et al (18)	2010	33	3× larger diameter than other venous segments from the access site	25-60	17	16	Aneurysmorrhaphy with PTFE mesh	93% (12 m) as.
Woo et al (41)	2010	19	-	40-70	3	16	Partial aneurysmectomy	92.2% (12 m)
Georgiadis et al (36)	2008	26	-	20-80	16	10	Excision and aneurysm repair with vein/prosthesis Rerouting technique	69±9% (12 m)
Balaz et al (40)	2008	4	-	-	4	0	Aneurysmorrhaphy with PTFE mesh	-
Shojaiefard et al (54)	2007	22	-	-	11	11	Partial aneurysmectomy	-
Lo and Tan (55)	2007	15	-	-	-	-	Plication	-
Pierce et al (56)	2007	12	-	28.1 ± 7.3	8	4	Aneurysmorrhaphy with stapler	-
Karabay et al (57)	2004	18	-	-	15	3	Partial aneurysmectomy	100% (6 m)
Najibi et al (58)	2002	2	-	30 and 35	1	1	Stent grafting	-
Cavallaro et al (59)	2000	26	-	-	26	0	Resection of aneurysm and reanastomosis of the stump Resection of aneurysm and creation of new fistula	-
Hakim et al (60)	1997	6	-	-	1	5	Aneurysmorrhaphy with stapler	-

According to the K/DOQI guidelines, the recommended diameter of a usable fistula is 6 mm (1), which represents a more than threefold diameter of a normal autologous vein (9, 10). In the literature review the treated aneurysm varies between 19.5 and 80 mm (Tab. I), representing more than three times the enlargement of the recommended diameter of a AVA vein. On the basis of these findings we suggest the following definition: “AVA aneurysm is a dilatation of all three vein layers with a minimal diameter of 18 mm” which represents three times the enlargement of a vein in a maturated AVA (3 × 6 mm = 18 mm) (Fig. 1).

Fig. 1 -

Mechanism of aneurysm development

The process of AVA aneurysm formation probably starts at the time of the creation of the AV access. This was confirmed by Martin et al (11), who studied the hemodynamic and geometric maturation of brachial AV accesses prospectively. Both the cephalic vein and the brachial artery increased their diameter from 2.29 to 6.31 mm, and from 3.76 to 5.39 mm, respectively, over an eight-week period post-surgery. The AVA thus generates a large pressure gradient between the high-pressure inflow artery and the low-resistance outflow vein, deviating an increased flow volume through the fistula (12). This combination of a low venous outflow resistance and the great ability of distention of the venous wall makes the arterialized vein capable of creating high flow rates under low pressure gradients (13). Thus, the venous arm of the fistula becomes tortuous under the arterial pressure because distention occurs both laterally and distally, and it is not stretched axially (14).

Another effect of the high blood flow in the vein is venous wall re-modeling (15). A physical explanation of this situation is well described by Laplace‘s law (T = P.R/t, T - wall tension, P - pressure, R - radius of the vessel, t - vessel thickness), when the wall tension is directly related to the radius of the vessel and intra-vessel pressure. Additionally, as the vessel dilates and the diameter enlarges, the wall tension increases, causing further vein dilation.

Central vein stenosis, usually as a result of prolonged central venous catheterization, is another hemodynamic factor leading to increased venous pressure, thus accelerating the aneurysm formation. In a study by Rajput et al (16), 78% of patients with symptomatic AVA aneurysms, which they defined as a focal dilatation of the outflow vein diameter greater than two times the normal caliber of the adjacent normal fistula vein segment, had a central vein stenosis requiring angioplasty. In the study by Shemesh et al (17) all patients (n = 20) with aneurysmal AVA treated with a stent graft had central vein stenoses. On the other hand, Berard et al (18) in a cohort of 38 patients found a concomitant central vein stenosis in only five patients (13%), and Pasklinsky et al (19) reported on 23 patients of whom four (17%) were found to have outflow vein stenosis. This discrepancy may be due to the fact that the fistulography and the assessment of the central venous system is not routinely performed in all patients, but only in candidates for stent grafting or if pre-operative US (ultrasound) assessment demonstrated an impairment of the fistula outflow due to the central vein stenosis.

Local irritation of the vein wall as a result of repeated cannulation during hemodialysis causes local tissue injury, necrosis and scaring, leading to a weakening of the vein wall. This small tissue defect in the cannulated part of the vein is sealed by fibrin plugs and subsequently replaced by connective tissue and accumulated to expand to the circumference of the puncture segments. In a retrospective study of 108 hemodialysis patients, in whom the “button hole” technique was used, the vascular diameters of the punctured segments were larger than those of the reference segments (20).

Classification of AVA aneurysm

To date, a classification system for AVA aneurysm is still lacking. We suggest that for a correct description, the following items be defined: (a) diameter (≥18 mm), (b) type of AVA, (c) definition of vein where aneurysm is present, (d) number of aneurysms and (e) type of aneurysm.

The type of AVA must be correctly defined according to the suggested nomenclature in the clinical practice recommendation of SVS (21). AVA aneurysms often occur along cannulation zones but can also occur in a non-cannulated outflow vein. A patient with a brachiocephalic fistula can develop a basilic vein aneurysm.

The types of AVA aneurysm are defined according to the presence of stenosis or thrombosis identified with ultrasonography or fistulography. We suggest dividing these into the four types (Fig. 2).

Fig. 2 -

Indications for treatment of AVA aneurysm

According to the K/DOQI guidance it is recommended that asymptomatic aneurysms of hemodialysis accesses do not require intervention and can be managed by abandoning cannulation of the aneurysmatic areas (1). Recently, the buttonhole technique of access cannulation has been recommended as a method which significantly reduces the existing aneurysm enlargement (22). An accurate definition of when the intervention is necessary is still lacking. Management is determined by an assessment of the skin condition, clinical signs and symptoms, ease of cannulation and functionality of the AVA. The diameter of the AVA aneurysm is not an indication for the treatment.

The main indication for treatment of an AVA aneurysm is its clinical presentation. Three main indications were identified through the literature search. A patient may have more than one indication for treatment.

Group A - related to patient discomfort

Pain overlying aneurysm is a rare symptom which may occur as a result of compression of a peripheral nerve by the aneurysm and the differential diagnosis is complicated by the high incidence of concomitant uremic or diabetic polyneuropathy (23). Therefore, other systemic causes must be excluded when the surgical treatment is under consideration. The reconstruction of an aneurysmal AVA for cosmetic reasons must be carefully considered and discussed with the patient with a focus on an explanation of the potential postoperative complications. Generally, the cosmetic aspect alone in an otherwise asymptomatic aneurysm is not an indication for the treatment.

Group B - related to bleeding prevention

Bleeding from an aneurysmal AVA is a severe and potentially lethal complication (24). This occurs most frequently after the hemodialysis needles have been removed, or can be spontaneous following rupture or a traumatic injury (which is rare). The predisposing factors for aneurysm bleeding are: thinning or erosion of the overlying skin layer resulting in fistula exposure, compromised skin with or without inflammation, a rapidly expanding aneurysm, hypertension, intra-access pressure, anticoagulations, ipsilateral extremity edema and prolonged bleeding time after the hemodialysis needle is removed. Bleeding can be present in all types of aneurysmal access except for type IV, in which the venous arm of the fistula is occluded with thrombus. In all patients with active bleeding and where the previously mentioned signs exist, immediate surgery is essential. In the case of acute bleeding associated with hemorrhagic shock, the ligation of access is the first, lifesaving procedure and the new hemodialysis access is usually constructed during the recovery period.

Group C - related with access flow

Inadequate blood flow may result in inadequate dialysis and is caused by impaired arterial inflow (25) or venous outflow stenosis between aneurysms, as well as lesions within the anastomotic area or in the central vein. The commonly used parameter to characterize the hemodynamic relevance of a stenosis is a reduction in vessel diameter exceeding 50% based on angiographic and/or US findings (1). A low flow is associated with aneurysm types II and III where the hemodynamic significant stenosis ≥50% is present according our suggested classification (Fig. 2). No flow through the fistula is associated with type IV, where the thrombus occludes the fistula. The treatment is focused on the lesion responsible for the low flow, which in the first instance would usually be by angioplasty of the stenosis in type II. In cases when the aneurysm is present with a risk of bleeding combined with stenosis an open surgical approach is recommended, although a covered stent is also an alternative with or without angioplasty. In type III the resection of aneurysm and replacement with venous or prosthetic conduit or aneurysmorrhaphy is recommended.

High-flow aneurysmal AV access may result in high-output congestive cardiac failure (CHF), or arterial steal syndrome. In the literature there are several studies focused on the treatment of high-flow aneurysmatic AVA (18, 34, 46). The largest study was published by Rokosny et al. where 24 (39%) patients were treated by aneurysmorrhaphy due to high-flow aneurysmatic AVA. The mean flow reduction was 2,197 mL/min AVA (34). Unfortunately, the precise definition when the high-flow aneurysmatic AVA is at risk for the development of CHF is not stated.

Generally, CHF is defined as the combination of high cardiac output (CO) with physical findings of systematic or pulmonary congestions, when CO in adults is >8 L/min or a cardiac index >3.9/min/m² (26).CHF is present in more than one-third of new dialysis patients (27) and pulmonary hypertension was described as having a 40-50% incidence in patients starting hemodialysis (28). The first study that examined the effect of AV access on CO published by Cohen et al showed that at baseline the patients with AV access had elevated CO (5.1 to 7.9 L/min) (29). Currently, there is no definition of when access flow (Qa) is too high. The concept of using the ratio Qa/CO (cardiopulmonary recirculation, CPR) has been proposed by Pandeya and Lindsay in their study of stable long-term HD patients. They found that the average Qa was 1.6 L/min and the average CO was 7.2 L/min, thus describing an average CPR of 22% (30). It has long been known that an AVA with an inappropriately high flow rate may be the cause of high-output HF (31, 32). According to the SVS Clinical practice guidelines for the placement and maintenance of arteriovenous hemodialysis access, the threshold for the upper limit of flow in most AVA is 2.5 L/min (5). MacRae et al suggested that the risk of high-flow access on the cardiac function would be entertained when the flow rate is >3 L/min or Qa/CO ≥ 30% (31). At present, no precise criteria exist for the preemptive treatment of patients with a high-flow aneurysmal AVA . We recommend treatment for all patients with aneurysmatic AVA with Qa >2.5 L/min who are in stage C (patients with current or past clinical heart failure) or in stage D (patients with end-stage refractory heart failure, who are candidates for extraordinary forms of therapy or for compassionate end-of-life care) classified according to the American College of Cardiology/American Heart Association (ACC/AHA) (33).

In asymptomatic patients we recommend the preemptive treatment in aneurysmal high-flow AVA when Qa > 3.0 L/min or Qa/CO ≥ 30% or cardiac index >5.0 L/min/m².

Treatment

Conservative treatment is indicated if an AVA is asymptomatic (indication group A). Conservative treatment consists of avoiding aneurysmatic areas for cannulation and using the modified buttonhole cannulation technique, which was recently proposed as a solution for fistulae with aneurysmal dilatations (35). Treatment is recommended for symptomatic AVA, which are presented with bleeding risk (indication group B) and with an inadequate flow (indication group C). Indications for treatment have already been discussed above.

For symptomatic aneurysmatic AVA, numerous case reports and small case series studies regarding treatment have been published. Several techniques have been proposed, including resection, a remodeling technique, stent grafting, resection with substitution, aneurysmorraphy or ligation. Each technique has advantages and disadvantages. Unfortunately, there are no randomized control trials, and it is difficult to compare different treatment modalities with an evidence-based approach. The main results are summarized in Table I, which represents all retrospective studies focused on the treatment of AVA aneurysm, published between April 1, 1967, and March 1, 2014. The resection of an aneurysm can be performed using either prosthetic or autologous (autogenous) material. The largest study was published by Georgiadis et al (36), in which an aneurysmal vein was resected and replaced with a prosthetic conduit in 24 patients with a 12-month primary patency of 57%. In a study by Pasklinsky et al (19), seven patients were treated by excision and repair using the great saphenous vein, and three patients by excision and repair with prosthetic material. The median follow-up was 19 months, and the primary patency rate at 12 months was 46.7%. The advantage of these techniques is the possibility of treating all types of access aneurysms, including those with thrombosis (Type III, IV), but these require that sufficient proximal and distal vein segment is free from thrombosis to allow the construction of end-to-end or end-to-side anastomoses. Additionally, the prosthetic conduit can be cannulated earlier rather than after an autogenous graft or a remodeling technique. The major disadvantages of the synthetic graft include increased risks of thrombosis and infection, compared to an autogenous graft (37).

The remodeling technique (partial aneurysmectomy—resection only of part of the aneurysmatic sac, plication, aneurysmorrhaphy—resection of aneurysmatic parts of the vein, reinforced aneurysmorrhaphy—resection of the aneurysmatic part and supporting of the vein with mesh external prosthesis), utilizes the native vein so the character of the fistula is preserved. Almehmi and Wang (38) treated 36 patients with partial aneurysmectomy, originally described in aortic and other aneurysms by Matas who named this technique aneurysmorraphy (39). Almehmi and Wang reported a primary patency rate for the fistula of 56% at 6 months (38). Their mean follow-up time was only 7.1 ± 4.8 months, however. A reinforced aneurysmorrhaphy with an external mesh prosthesis was developed by Balaz et al (40) and later tested by Berard et al (18) in 33 patients with an assisted primary patency of 93% at 12 months. The largest series in 62 patients was reported by Rokosny et al (34) with a primary patency of 86% at 6 months (the mean follow-up time was 14.66 ± 12.80 months). Even when the reinforced aneurysmorrhaphy uses a prosthetic support the infection rate is lower than 5% (18, 34).

Woo et al (41) performed an aneurysmorrhaphy without an external mesh prosthesis in 19 patients, with a median follow-up of 23 months. They observed a median primary patency of 14 months. The effect of the external support of the weakened vein after aneurysmorrhaphy for maintaining the patency is not clear, and more comparative studies are needed. The aneurysmorrhaphy technique should be used for the treatment of aneurysm type I and II. In patients with a high-flow fistula aneurysmorrhaphy can be accompanied by a reduction of the arterial anastomosis or with reposition of AV anastomosis to a low-flow artery (18, 34). Other remodeling salvage techniques described in the literature include plication (36) and lateral venorrhaphy with a stapler (40, 42). Unfortunately, the study populations of these studies are very small, the follow-up is short and the patency and complication rates are not described clearly.

There has been a rapid increase in the use of endovascular techniques in vascular surgery incorporated into the management of AVA. The first reported successful use of a covered stent to treat AVA aneurysm was reported by Allaria et al in 2002 (43).Recently, Shemesh et al (17) described the use of stent grafts to treat nine graft access pseudoaneurysms and 11 AVA aneurysms with a functional patency rate of 87% at 12 months and a median follow-up of 15 (6.3-55.5) months. Although their patency rate is comparable to the previously described techniques, they excluded patients with steal syndrome, aneurysms close to the anastomosis and large aneurysms lacking a stent graft sealing zone. The advantage of using a stent graft is that it can be performed as an outpatient procedure and early venipuncture is encouraged to allow the patient an uninterrupted dialysis regimen (44, 45). Based upon the available evidence, the stent graft should be considered in patients with type I, II and III aneurysms, without presence of infection.

Ligation should be considered when the previously described salvage technique is unsuccessful or acute bleeding in an unstable patient occurs. Another indication is a patient who is successfully treated with a renal transplantation with the expectation of a good long-term function.

Conclusions

AVA aneurysm is characterized by an enlargement of all three vessel layers with a diameter of more than 18 mm and can be presented in four types (I-IV) according to the presence of stenosis and/or thrombosis. In contrast to arterial aneurysm, the diameter of the AVA aneurysm is not an indication for treatment; this is based on the clinical status of the patient with bleeding prevention and inadequate access flow. According to AVA aneurysm symptoms, we divided the aneurysm on asymptomatic and symptomatic AVA aneurysm. In an asymptomatic aneurysm a conservative treatment is recommended using the buttonhole cannulation technique, which reduces the further development of an aneurysm. In a symptomatic aneurysm several techniques have been suggested. Even though we lack evidence regarding which surgical treatment option is the method of choice, we recommend as a first-line option a technique which utilizes the native vein so that the character of the AVA is preserved. Recently, the best long-term results were achieved by using aneurysmorrhaphy with or without a prosthetic support. The replacement of an aneurysm with autogenous or prosthetic conduit is also another option showing good long-term results; however, the complication rate is higher than in the technique using the native vein. Finally, using a stent graft is an elegant and non-invasive method for the treatment of aneurysmatic AVA. The main limitation in using this technique is that the aneurysm must have an adequate “sealing zone” for the stent graft and there is a relatively high cost for the stent graft. Generally stent grafting of an AVA aneurysm as a quick and non-invasive technique is recommended for urgent treatment in bleeding patients who are at high risk. Further research is warranted and we expect that the suggested classification system of AVA access, which is the first classification in this field, may facilitate comparisons of different study cohorts in the future.

Symptomatic high-flow radiocephalic AVA aneurysm (a), symptomatic rapidly expanding brachiocephalic AVA aneurysm (b), asymptomatic radiocephalic AVA aneurysm (c). AVA = arteriovenous access.

Suggested classification of arteriovenous access aneurysm. Type I—without stenosis and thrombosis; Type II—with hemodynamic significant stenosis (≥50%) (A) in inflow artery, (B) at arterial anastomosis, (C) along cannulation zone, (D) in the central vein; Type III—with partial thrombosis occluding ≥50% of the lumen.; Type IV—with complete thrombosis.

• 1. Vascular Access Work Group. Clinical practice guidelines for vascular access. Am J Kidney Dis 2006 48 Suppl 1 S248 S273
• 2. Rooijens PP Tordoir JH Stijnen T Burgmans JS Smet de AA Yo TI Radiocephalic wrist arteriovenous fistula for hemodialysis: meta-analysis indicates a high primary failure rate. Eur J Vasc Endovasc Surg 2004 28 6 583 589
• 3. Huber TS Carter JW Carter RL Seeger JM Patency of autogenous and polytetrafluoroethylene upper extremity arteriovenous hemodialysis accesses: a systematic review. J Vasc Surg 2003 38 5 1005 1011
• 4. Salahi H Fazelzadeh A Mehdizadeh A Razmkon A Malek-Hosseini SA Complications of arteriovenous fistula in dialysis patients. Transplant Proc 2006 38 5 1261 1264
• 5. Padberg FT Jr Calligaro KD Sidawy AN Complications of arteriovenous hemodialysis access: recognition and management. J Vasc Surg 2008 48 5 Suppl 55S 80S
• 6. http://www.vascularaccesssociety.com/guidelines.html
• 7. Liberati A Altman DG Tetzlaff J et al. The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration. PLoS Med 2009 6 7 e1000100
• 8. Vesely TM Vascular access terminology. Semin Dial 2007 20 4 372 author reply 372-373.
• 9. Spivack DE Kelly P Gaughan JP van Bemmelen PS Mapping of superficial extremity veins: normal diameters and trends in a vascular patient-population. Ultrasound Med Biol 2012 38 2 190 194
• 10. Shenoy S Surgical anatomy of upper arm: what is needed for AVF planning. J Vasc Access 2009 10 4 223 232
• 11. Martin AG Grasty M Lear PA Haemodynamics of brachial arteriovenous fistula development. J Vasc Access 2000 1 2 54 59
• 12. Georgakarakos EI Kapoulas KC Georgiadis GS Tsangaris AS Nikolopoulos ES Lazarides MK An overview of the hemodynamic aspects of the blood flow in the venous outflow tract of the arteriovenous fistula. J Vasc Access 2012 13 3 271 278
• 13. Zócalo Y Pessana F Santana DB Armentano RL Regional differences in vein wall dynamics under arterial hemodynamic conditions: comparison with arteries. Artif Organs 2006 30 4 265 275
• 14. Han HC Zhao L Huang M Hou LS Huang YT Kuang ZB Postsurgical changes of the opening angle of canine autogenous vein graft. J Biomech Eng 1998 120 2 211 216
• 15. Martinez R Fierro CA Shireman PK Han HC Mechanical buckling of veins under internal pressure. Ann Biomed Eng 2010 38 4 1345 1353
• 16. Rajput A Rajan DK Simons ME et al. Venous aneurysms in autogenous hemodialysis fistulas: is there an association with venous outflow stenosis. J Vasc Access 2013 14 2 126 130
• 17. Shemesh D Goldin I Zaghal I Berelowitz D Verstandig AG Olsha O Stent graft treatment for hemodialysis access aneurysms. J Vasc Surg 2011 54 4 1088 1094
• 18. Berard X Brizzi V Mayeux S Sassoust G Biscay D Ducasse E Bordenave L Corpataux JM Midy D Salvage treatment for venous aneurysm complicating vascular access arteriovenous fistula: use of an exoprosthesis to reinforce the vein after aneurysmorrhaphy. Eur J Vasc Endovasc Surg 2010 40 1 100 106
• 19. Pasklinsky G Meisner RJ Labropoulos N et al. Management of true aneurysms of hemodialysis access fistulas. J Vasc Surg 2011 53 5 1291 1297
• 20. Hsiao JF Chou HH Hsu LA et al. Vascular changes at the puncture segments of arteriovenous fistula for hemodialysis access. J Vasc Surg 2010 52 3 669 673
• 21. Sidawy AN Gray R Besarab A et al. Recommended standards for reports dealing with arteriovenous hemodialysis accesses. J Vasc Surg 2002 35 3 603 610
• 22. Vaux E King J lloyd S Moore J Bailey L Reading I Naik R Effect of buttonhole cannulation with a polycarbonate peg on in-center hemodialysis fistula outcomes: a randomized controlled trial. Am J Kidney Dis 2013 62 1 81 8
• 23. Bolton CF Peripheral neuropathies associated with chronic renal failure. Can J Neurol Sci 1980 7 2 89 96
• 24. Ellingson KD Palekar RS Lucero CA et al. Vascular access hemorrhages contribute to deaths among hemodialysis patients. Kidney Int 2012 82 6 686 692
• 25. Schanzer A Nguyen LL Owens CD Schanzer H Use of digital pressure measurements for the diagnosis of AV access-induced hand ischemia. Vasc Med 2006 11 4 227 231
• 26. Wasse H Singapuri MS High-output heart failure: how to define it, when to treat it, and how to treat it. Semin Nephrol 2012 32 6 551 557
• 27. Collins AJ Cardiovascular mortality in end-stage renal disease. Am J Med Sci 2003 325 4 163 167
• 28. Yigla M Nakhoul F Sabag A et al. Pulmonary hypertension in patients with end-stage renal disease. Chest 2003 123 5 1577 1582
• 29. Cohen SM Edholm OG Howarth S et al. Cardiac output and peripheral blood flow in arteriovenous aneurysm. Clin Sci (Lond) 1948 7 1 35 47
• 30. Pandeya S Lindsay RM The relationship between cardiac output and access flow during hemodialysis. ASAIO J 1999 45 3 135 138
• 31. MacRae JM Pandeya S Humen DP Krivitski N Lindsay RM Arteriovenous fistula-associated high-output cardiac failure: a review of mechanisms. Am J Kidney Dis 2004 43 5 e17 e22
• 32. Stern AB Klemmer PJ High-output heart failure secondary to arteriovenous fistula. Hemodial Int. 2011 15 1 104 107
• 33. Hunt SA American College of Cardiology; American Heart Association Task Force on Practice Guidelines (Writing Committee to Update the 2001 Guidelines for the Evaluation and Management of Heart Failure). ACC/AHA 2005 guideline update for the diagnosis and management of chronic heart failure in the adult: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Update the 2001 Guidelines for the Evaluation and Management of Heart Failure) J Am Coll Cardiol 2005 46 6 e1 e82
• 34. Rokosny S Balaz P Wohlfahrt P Palous D Janoušek L Reinforced aneurysmorrhaphy for true aneurysmal haemodialysis vascular access. Eur J Vasc Endovasc Surg 2014 47 4 444 450
• 35. Marticorena RM Hunter J Macleod S et al. The salvage of aneurysmal fistulae utilizing a modified buttonhole cannulation technique and multiple cannulators. Hemodial Int 2006 10 2 193 200
• 36. Georgiadis GS Lazarides MK Panagoutsos SA et al. Surgical revision of complicated false and true vascular access-related aneurysms. J Vasc Surg 2008 47 6 1284 1291 1291 e5
• 37. Akoh JA Prosthetic arteriovenous grafts for hemodialysis. J Vasc Access 2009 10 3 137 147
• 38. Almehmi A Wang S Partial aneurysmectomy is effective in managing aneurysm-associated complications of arteriovenous fistulae for hemodialysis: case series and literature review. Semin Dial 2012 25 3 357 364
• 39. Matas RI An operation for the radical cure of aneurism based upon arteriorrhaphy. Ann Surg 1903 37 2 161 196
• 40. Balaz P Rokosny S Klein D Adamec M Aneurysmorrhaphy is an easy technique for arteriovenous fistula salvage. J Vasc Access 2008 9 2 81 84
• 41. Woo K Cook PR Garg J Hye RJ Canty TG Midterm results of a novel technique to salvage autogenous dialysis access in aneurysmal arteriovenous fistulas. J Vasc Surg 2010 51 4 921 925 925e1
• 42. Englesbe MJ Wu AH Clowes AW Zierler RE The prevalence and natural history of aortic aneurysms in heart and abdominal organ transplant patients. J Vasc Surg 2003 37 1 27 31
• 43. Allaria PM Costantini E Lucatello A Gandini E Caligara F Giangrande A Aneurysm of arteriovenous fistula in uremic patients: is endograft a viable therapeutic approach? J Vasc Access 2002 3 2 85 88
• 44. Barshes NR Annambhotla S Bechara C et al. Endovascular repair of hemodialysis graft-related pseudoaneurysm: an alternative treatment strategy in salvaging failing dialysis access. Vasc Endovasc Surg 2008 42 3 228 234
• 45. Pandolfe LR Malamis AP Pierce K Borge MA Treatment of hemodialysis graft pseudoaneurysms with stent grafts: institutional experience and review of the literature. Semin Intervent Radiol 2009 26 2 89 95
• 46. Hossny A Partial aneurysmectomy for salvage of autogenous arteriovenous fistula with complicated venous aneurysms. J Vasc Surg 2014 59 4 1073 1077
• 47. Zink JN Netzley R Erzurum V Wright D Complications of endovascular grafts in the treatment of pseudoaneurysms and stenoses in arteriovenous access. J Vasc Surg 2013 57 1 144 148
• 48. Kinning AJ Becker RW Fortin GJ Molnar RG Dall’Olmo CA Endograft salvage of hemodialysis accesses threatened by pseudoaneurysms. J Vasc Surg 2013 57 1 137 143
• 49. Belli S Parlakgumus A Colakoglu T et al. Surgical treatment modalities for complicated aneurysms and pseudoaneurysms of arteriovenous fistulas. J Vasc Access 2012 13 4 438 445
• 50. Shah AS Valdes J Charlton-Ouw KM et al. Endovascular treatment of hemodialysis access pseudoaneurysms. J Vasc Surg 2012 55 4 1058 1062
• 51. Bachleda P Utíkal P Kalinová L Váchalová M Surgical remodelling of haemodialysis fistula aneurysms. Ann Acad Med Singapore 2011 40 3 136 139
• 52. Ekim H Odabasi D Basel H Aydin C Management of giant venous aneurysm secondary to arteriovenous fistula in hemodialysis patients. Pak J Med Sci 2011 27 5 1028 1032
• 53. Karatepe C Yetim TD Treatment of aneurysm of hemodialysis access arteriovenous fistula. Turkish J Thorac Cardiovasc Surg 2011 19 4 566 569
• 54. Shojaiefard A Khorgami Z Kouhi A Kohan L Surgical management of aneurysmal dilation of vein and pseudoaneurysm complicating hemodialysis arteriovenuos fistula. Indian J Surg 2007 69 6 230 236
• 55. Lo HY Tan SG Arteriovenous fistula aneurysm—plicate, not ligate. Ann Acad Med Singapore 2007 36 10 851 853
• 56. Pierce GE Thomas JH Fenton JR Novel repair of venous aneurysms secondary to arteriovenous dialysis fistulae. Vasc Endovasc Surg 2007 41 1 55 60
• 57. Karabay O Yetkin U Silistreli E Uskent H Onol H Açikel U Surgical management of giant aneurysms complicating arteriovenous fistulae. J Int Med Res 2004 32 2 214 217
• 58. Najibi S Bush RL Terramani TT Chalkof EG Gunnoud AB Lumsden AB Weiss VJ Covered stent exclusion of dialysis access pseudoaneurysms. J Surg Res 2002 106 1 15 9
• 59. Cavallaro G Taranto F Cavallaro E Quatra F Vascular complications of native arteriovenous fistulas for hemodialysis: role of microsurgery. Microsurgery 2000 20 5 252 254
• 60. Hakim NS Romagnoli J Contis JC Akoh J Papalois VE Refashioning of an aneurysmatic arterio-venous fistula by using the multifire GIA 60 surgical stapler. Int Surg 1997 82 4 376 377