End-to-side versus side-to-side anastomosis with distal vein ligation for arteriovenous fistula creation

Abstract

Introduction

There is lack of compelling evidence about the best technique to carry out the anastomosis between the artery and the vein: end to side or side to side. This issue was addressed by very few randomized controlled studies. This topic has recently re-emerged with the advent of the endovascular fistula creation using the side-to-side technique.

Objectives: To compare the results of both surgical techniques for the creation of arteriovenous anastomosis.

Methods

This is a randomized controlled prospective study. All renal failure patients, 18 years and older, referred to our institution requiring creation of a new arm arteriovenous fistulas, including distal radio-cephalic, ulno-basilic, proximal brachio-cephalic or brachio-basilic configurations were included.

Results

Between February 2018 and October 2018, 378 patients underwent creation of permanent haemodialysis access. A total of 100 patients were randomized equally into the end-to-side and side-to-side groups. Follow-up for the study purpose continued until May 2019 (mean = 9 months, range 1–12). Patients’ age ranged from 19 to 68 years. Sevety-seven arteriovenous fistulas were created at the elbow (37 brachio-basilic and 40 brachio-cephalic). Radio-cephalic fistulae were 23, created at wrist and in the forearm. Primary technical success was 97%, and 35 (70%) and 17 (34%) cases achieved functionally maturation in the end-to-side and side-to-side groups, respectively (P = 0.0001). Primary and secondary patency rates at 12 months were 76% end to side versus 78% STS (P = 0.381) and 84% end to side versus 86% STS (P = 0.225), respectively.

Conclusion

End-to-side technique should be used in all instances of arteriovenous fistulas creation.

Keywords

End to side side to side AV fistula dialysis technique and procedures

Introduction

Arteriovenous fistula (AVF) is the lifeline for patients with chronic renal failure on haemodialysis. The international guidelines recommend that patients should be referred for access creation three to six months prior to predicted haemodialysis dates. The preferred sites for access placement are distal arm AVF, proximal arm AVF, basillic vein transposition or graft insertion, respectively.¹

Both meticulous preoperative assessment and patient selection are fundamental for achieving functioning AVF with long-term patency. AVF maintenance always requires multi-disciplinary approach, with surgeons, nephrologist, dialysis nurses and the patients themselves working hand in hand. Any break in this circle will ultimately lead to failure of the AVF, and consequently, failure of haemodialysis.²

Surgical technique is of paramount importance for long-term patency of AVF. There are two commonly known techniques to carry out the anastomosis between the veins to the artery: end to side (ETS) and side to side (STS). There is a lack of compelling evidence to support the superiority of either of those techniques. This issue was addressed by very few studies.^3–7 In the late eighties of the last century, Wedgwood’s publication comparing both techniques concluded that the ETS anastomosis was ‘the one of choice’ in creation of AVF.⁸ Many publications followed, with conflicting results, making it difficult to decide which one is superior to the other. Some studies concluded that the STS configuration showed early maturation and higher cumulative patency rates.⁹ On the other hand, studies supporting ETS configuration showed higher patency and lower complication rates for this technique.^3,6 This debate has re-emerged with the recent advent in endovascular percutaneous AVF (pAVF) creation. The increasing popularity of the pAVF devices using the same technique of STS anastomosis is also being promoted for having higher patency rates with recent long-term results published.^10,11

Aim of the study

To compare the results of both surgical techniques for creation of arteriovenous anastomosis, ETS versus STS artery in terms of patency, maturation, functionality and complication rates in a randomized prospective controlled setting.

Patients and methods

This is a randomized controlled prospective study. All renal failure patients, 18 years and older, referred to our institution requiring creation of a new arm AVF, including distal radio-cephalic, ulno-basilic, proximal brachio-cephalic or brachio-basilic configurations were considered for recruitment.

We excluded patients planned for revision, synthetic graft or lower limb AVFs. Also, patients with absent distal pulses and chronic ischaemia of the upper limb were not considered for the procedure. Recent cannulation of puncture of the vein within two weeks before its use in AVF creation delayed the procedure for six-weeks post-cannulation and required re-assessment. All included patients gave appropriate written consent.

The primary end point was functional maturation, defined as the ability of the access to withstand six consecutive full dialysis sessions within a period of 30 days. Created AVFs were considered for functional maturation if they achieved the rule of 6 (6 mm vein diameter and 600 ml/min flow, and less than 6 mm vein depth). Secondary end points reported included patency, dialysis flow rates, complications rate, failure of maturation, bleeding, infection, steal syndrome and aneurysmal dilatation at anastomosis site.

All patients underwent clinical assessment as well as routine duplex scan for marking of the artery and a patent vein suitable for creation of AVF prior to randomization. A minimum-acceptable vein diameter was set at 2.5 mm for distal fistula and 3 mm for proximal ones. Minimum-accepted arterial diameter was 2 mm for distal AVFs and 2.5 mm for proximal sites.

Computer-based randomization with sealed envelopes was the method adopted to allocate patients equally into the ETS versus STS groups. Computer-generated random-size block numbers were used. The key sheet was kept by an independent party and only revealed for final results analysis.

All patients were blinded to the technique of the procedure. Patients underwent the procedure under general, local anaesthetic or regional block according to suitability and patients’ preference. Creation of fistula was performed using 6/0 prolene for anastomosis in continuous sutures, either ETS or STS, with ligation of the distal end of the vein. Arteriotomy size ranged from 7 to 10 mm for proximal AVF and from 12 to 15 mm for distal AVF according to the size of the artery. All brachio-basilic fistulae were created in two stages. All procedures were created by experienced access surgeons with more than 100 access procedures performed.

Post-operative follow-up was carried out during patients’ routine review in clinic on first and sixth weeks, then at three and six months after surgery. Duplex scans were performed by a qualified vascular radiologist for the assessment of patency on these visits. Duplex scan was also used to look at flow rates and anastomotic stenosis. All assessors and data recorders were blinded to the result of randomization.

Ethical approval was acquired from the medical ethics committee of Mansoura University.

The study was registered at Clinicaltrials.gov under record number: R.18.02.24 – 2018/02/04. There were no specific funds allocated to the study, and there were not any conflicts of interest reported by any of the authors.

Statistical analysis was performed using the IBM SPSS 21 version (IBM SPSS Statistics for Windows, version 21.0, Armonk, NY: IBM Corp.). Comparisons were carried out using ANOVA test, Mann–Whitney U test and Fisher’s exact test where suitable.

Sample-size calculation was performed with the assumption being made that ETS fistulae are more likely to reach functional maturation than STS fistulae. We estimated the number of patients needed in a superiority trial with an effect size of 95% and a margin of 10 (alpha 5%, power 80%) to be 100 patients to reach sufficient evidence and avoid a type 2 error.

Results

Between February 2018 and October 2018, 378 patients underwent creation of permanent haemodialysis access (including 295 AVFs, 31 AV synthetic grafts and 52 permanent dialysis catheters) in our institution. After exclusion of unsuitable patients as defined by the aforementioned criteria, and patients unwilling to participate in the study, 100 patients were randomized equally into the ETS and STS groups. Follow-up for the study purpose continued until May 2019 (mean = nine months, range 1–12). Routine patient follow-up continued thereafter. Study flow chart is illustrated in Figure 1.

Figure 1.

CONSORT flow diagram.

Patients’ age ranged from 19 to 68 years. There was no statistically significant difference between the two groups in terms of demographics and co-morbidities (Table 1).

Table 1.

Patients’ demographics and co-morbidities.

	ETS	STS	P-value
Age (mean)	37.8 (19–67)	39.1 (21–68)	0.349
Male gender (count)	31	29	0.685
Smoking (count)	12	17	0.187
Diabetic mellitus(count)	9	15	0.816
Hypertension(count)	30	31	0.682
Referred pre-dialysis(count)	25	27	0.564

As regard to the site of the fistula, 77 were created at the elbow (37 brachio-basilic and 40 brachio-cephalic AVFs). Radio-cephalic AVFs were 23, created at the wrist and in the forearm. There was no statistically significant difference between the two groups in terms of AVF site (P = 0.172). Details in terms of inter-group differences are shown in Figure 2.

Figure 2.

Fistula site.

Mean operative times were 49 and 54 min in ETS and STS groups, respectively (P = 0.391). Primary technical success demonstrated by easily palpable thrill and good machinery Doppler signals over the vein was achieved in 97% of cases. On-table weak thrill or pulse was felt in three patients: two cases in STS group and one case in ETS group (P = 0.124). One case (STS group) thrombosed on the first follow-up visit, while the other two remained patent but failed to reach functional maturation and ultimately required revision or re-citation. Post-operative follow-up clinically and with Duplex scan took place in the outpatient department at weeks 1 and 6 and months 3 and 6 post-operatively.

A total of five cases were lost to follow-up, all after a minimum of three months (two cases in ETS and three in STS groups).

In the ETS and STS groups, 35 and 17 cases achieved functionally maturation, respectively (P = 0.0001) (Figure 3).

Figure 3.

Functional maturation between groups.

Overall, 16 cases in EST groups dialyzed at 400 ml/min rate, where only two cases of STS group did in the first three dialysis sessions. There was a significant difference between the two groups in terms of achieving more than 300 ml/min dialysis rates in favour of the ETS group (P = 0.024). Details are presented in Figure 4.

Figure 4.

Dialysis flow rate between groups (best achieved in first three sessions).

In terms of complications reported over the period of follow-up, two cases suffered surgical site infection in each group (P = 0.984). Six cases developed a haematoma (1 ETS vs. 5 STS, P = 0.058), nine cases became thrombosed (4 ETS vs. 5 STS, P = 0.835), three cases developed pseudoaneurysms (2 ETS vs. 1 STS, P = 0.061) and only one case in the STS group ruptured after three months (P = 0.427). Steal syndrome complicated two cases in ETS group and four in STS group (P = 0.064). All cases suffered from steal syndrome were proximal fistulas created using brachial artery. Of those, five cases were managed conservatively, and only one case required surgical repair with distal revascularization interval ligation in the STS group.

Primary and secondary patency rates at 12 months were 76% ETS vs. 78% STS (P = 0.381) and 84% ETS vs. 86%STS (P = 0.225), respectively. Details are illustrated in Table 2. Ultrasound criteria of the utilized vein are shown in Table 3. There was no significant difference between the two groups in terms of pre-operative vein diameter or depth. On the opposite hand, three and six-months follow-up duplex scans showed highly significant difference in terms of vein diameter and flow rates in favour of ETS group. These data are shown in Table 3.

Table 2.

Post-operative complications.

Complications	ETS (N = 50)	STS (N = 50)	P value
Infection	2	2	0.984
Haematoma	1	5	0.058
Thrombosis	4	5	0.835
Pseudoaneurysm	2	1	0.061
Rupture	0	1	0.427
Steal	2	4	0.064
One-year 1ry patency	76%	78%	0.381
One-year 2ry patency	84%	86%	0.225

Table 3.

Comparison between the two groups including clinical and duplex follow-up.

	Type of anastomosis				P-value
	End to side		Side to side
	Mean	Count	Mean	Count
Pre-op vein diameter (mm)
Vein diameters	3.29		3.28		0.382
Less than 2 mm		2		0	0.287
From 2 to 3 mm		3		5
More than 3 mm		45		45
Pre-op vein depth (mm)	5.84		6.11		0.148
Intraoperative thrill					0.570
No thrill		0		0
Good thrill		48		48
Weak thrill		1		2
First-week follow-up
No thrill		0		0	0.558
Good thrill		48		49
Weak thrill		2		1
Third-month follow-up
No thrill		0		0	0.320
Good thrill		48		48
Weak thrill		0		1
Sixth-month follow-up
No thrill		0		0	0.570
Good thrill		48		48
Weak thrill		1		2
Third-month follow-up duplex diameter (mm)	6.9		5.2		0.001
Sixth-month follow-up duplex diameter (mm)	8.6		6.4		0.001
Third-month duplex flow rate (ml/min)	1111		636		0.001
Sixth-month duplex flow rate (ml/min)	1319		796		0.001

Discussion

The annual incidence of patients starting renal replacement therapy is on the rise worldwide. Haemodialysis constitutes the majority of treatment for patients with end-stage renal disease (ESRD). Native vein AVF is reported to have the best patency and functional maturation rates amongst all other options.¹² This poses an overwhelming load on the shoulders of dialysis access surgeons to insure optimal surgical technique when continuously performing the creation of AVF.

Our hospital is a high-volume tertiary referral centre covering over 15 million population in the Delta area of Egypt, known to be endemic for ESRD, with a work load of more than 800 procedures performed yearly for the past 10 years. This promotes continuous efforts to improve technical success and patency rates of dialysis access creation. Creating AVF with both techniques has been a standard of care in our centre, and surgeons were trained to be able to adopt both techniques as seen anatomically suitable for each patient. This has led to the formulation of this study aiming to answer the question of which is the best technique in terms of late outcome when both are anatomically feasible.

Comparison between ETS and STS methods for anastomosis of the artery and vein was probably first reported by Wedgwood⁸ in 1984. Both techniques seemed to lead to a similar outcome in terms of technical success and patency, although he reported slightly higher number of complications in the STS group and hence suggested that ETS might be the technique of choice. On the other hand, STS technique was viewed by some authors to be easier to perform, with better patency rates.^4,13 The debate continued with only few prospective randomized trials addressing this question.^3–7

Our study demonstrated that both techniques had high success and patency rates with no significant differences statistically. Also, complications rates were more or less the same, although the incidence of haematoma was almost significantly higher in the STS group (P = 0.058). This might be attributed to the extra dissection of tissues required to bring the vein into closer proximity to the artery. The incidence of steal was doubled in the STS group but did not reach statistical significance (P = 0.064). Although non-significant, the tendency to make larger arteriotomies and venotomies to facilitate STS anastomosis may be the reason behind this finding. These results are consistent with those reported by some randomized controlled and observational studies.^3–8,13,14

In our study population, nine AVFs thrombosed, with four successful thrombectomies and two thrombolysis procedures required to restore their patency. There was one rupture complicating AVF due to late infection of a brachio-basilic fistula in a diabetic patient. This patient was treated with ligation and debridement. Steal syndrome was observed in six patients, four of them were also diabetic. Although the small number of diabetic patients did not allow for a significant subgroup analysis, these observations reflect the higher risk of complications incurred with diabetic patients. A total of five cases were lost to follow-up. All of these patients had a minimum of three months of follow-up (two cases in ETS and three cases in STS groups); thus, it did not affect the analysis in terms of primary end point.

The definition of functional maturation of AVF was consistently reported in the literature as ‘The ability of the access to withstand 6 consecutive full dialysis sessions within a period of 30 days’.¹⁵ This parameter showed the most significant difference between the two groups of the study population, with clear favour for the ETS technique (P = 0.0001). This was also reflected in the results of maximum flow achieved during the first three dialysis sessions (Figure 4).

There was no significant difference between the two groups with regards to patency as shown in the study. Although a fistula might remain patent for a long time, it might not be functioning to achieve adequate dialysis. This study highlights this point as it illustrates the significant difference between the two groups (in favour of the end-to-side) with regards to functionality despite the absence of this difference in patency. Ultrasound data confirms higher vein dilatation and higher flow rates in ETS group compared to STS (P = 0.0001).

The recent advances in the endovascular creation of AVF using different percutaneous devices are currently being strongly promoted to nephrologists and interventional radiologists. Recent publications of long-term results suggested high patency rates and low complications.^10,11 Although cost and operative times are still of major concerns, this study also suggests that the STS anastomosis used in this technique may have lower long-term maturation and functionality compared to standard ETS surgical fistula.

Study limitations

We realize that the number of patients recruited in both groups does not allow for meaningful subgroup analysis. Patients with ESRD on haemodialysis are almost certainly very well informed about their disease and the possible complications and long-term problems with dialysis access. Recruitment for randomized controlled trials in such cohort of patients has proven to be difficult.

It is understandable that there are variations in the surgeons’ experience and their techniques. AVF creation is probably very straightforward well-standardized procedure. Also, all our procedures were carried out by experienced access surgeons. It is nearly impossible to avoid all bias possible due to variations between surgeons, and this reflects the real-world experience.

Conclusion

Considering these results, we recommend that ETS technique should be used at all instances when creating AVF. Although some surgeons might be tempted to adopt the STS technique as they may find it somewhat easier, they should consider the long-term benefits of the ETS technique.

Highlights

Type of research: Single-centre prospective randomized controlled study.

Key findings: Functional maturation was compared in 100 instances of haemodialysis arteriovenous fistulas (AVF) created with end-to-side (ETS) and side-to-side (STS) techniques equally randomized in the two groups. Of them, 70% of ETS and 34% of STS cases achieved functionally maturation (P = 0.0001).

Take home message: We recommend that ETS technique should be used at all instances when creating AVF.

Table of contents summary: This single-centre prospective randomized controlled study compared the results of ETS and STS surgical techniques for creation of haemodialysis arteriovenous fistulas with regards to functional maturation, technical success and complications rates in 100 patients. Results demonstrated significant difference in terms of functional maturation in favour of the end-to-side technique. The authors recommend the use of this technique in all instances.

Supplemental Material

sj-pdf-1-vas-10.1177_1708538120976993 - Supplemental material for End-to-side versus side-to-side anastomosis with distal vein ligation for arteriovenous fistula creation

Supplemental material, sj-pdf-1-vas-10.1177_1708538120976993 for End-to-side versus side-to-side anastomosis with distal vein ligation for arteriovenous fistula creation by Mohammed ElKassaby, Nashaat Elsayed, Ahmed Mosaad and Mosaad Soliman in Vascular

Footnotes

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Mohammed ElKassaby

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