AUTOGENOUS ARTERIOVENOUS ELBOW FISTULA FOR HAEMODIALYSIS AND UPPER EXTREMITY ISCHEMIA

BACKGROUND
The autogenous brachiocephalic or brachiobasilic arteriovenous elbow fistula is not considered to be only the secondary haemodialysis access. In patients with an unsuitable forearm vessel bundle, it is indicated as primary access and it is the method preferred to the fistula creation using a vascular prosthesis. Its rather rare complication is the development of upper extremity ischemia.


AIM
To summarise current knowledge of this fistula type and its associated complications


METHODS
Review of the literature.


RESULTS
The creation and maturation of the fistula and occurrence of the steal syndrome is influenced by a number of factors. The analysis and awareness of such factors will provide for creation of a suitable fistula as well as for timely complication diagnostics and treatment.


CONCLUSIONS
The autogenous elbow fistula utilising the brachial artery and the cephalic or basilic vein in the upper extremity represents a high-quality haemodialysis access. Its potential complication is the occurrence of the steal syndrome. Its occurrence and manifestations do not constitute indications for ligation of the access. The gathered information shows that a suitable surgical procedure can help meet the basic rule for haemodialysis access--resolving the ischemia and maintaining the access.


INTRODUCTION
The creation of a quality arteriovenous (AV) fi stula for haemodialysis is dependent on a relatively healthy and undamaged arterial and subcutaneous venous bed.The standard primary AV fi stula in Europe is the Brescia-Cimino fi stula 1 or a modifi cation thereof.
The autogenous AV fi stula in elbow, which utilises the rich subcutaneous venous bed, is mainly considered the "secondary" access after having exhausted all the possibilities of fi stula creation at the more distal level 2 .Today older, polymorbid patients are dialysed with lower quality distal forearm vascular bundle, unsuitable for AV fi stula creation, and elbow fi stula becomes the primary access.The cephalic or basilic veins are arterialised via the brachial artery.
In 1970 Cascardo et al. 3 published their experience in creating elbow AV fi stulas for low-quality forearm arterial bed.The use of the basilic vein is described by Dagher 4 .Use of the perforating vein for anastomosis was published by Gracz 5 .10-25 % of cases of the brachiocephalic and brachiobasilic AV fi stulas show steal syndrome presentations.

METHODS
Using the Pubmed database, relevant publications were found on creation of the autogenous arteriovenous fi stulas for haemodialysis in the elbow with a focus on the occurrence of the steal syndrome and upper extremity ischemia.

RESULTS
The method of primary arteriovenous fi stula creation is diff erent in Europe and in the U.S.A.Primary autogenous fi stula is created in 80 % of patients in Europe compared to 24 % in the U.S. 6 .In the early 1990s, the method of choice in the U.S. was the AV fi stula using an ePTFE graft, which ensured high blood fl ow rates of the fi stula 7 .The complications associated with these fi stulas are wellknown and are predominantly of stenotic and thrombotic nature [8][9][10] .In the mid-1990s, the situation was reviewed in the U.S., following the DOQI recommendation, and revival of the autogenous fi stulas took place due to less proneness to stenoses, thromboses and infectious complications in comparison with the grafts.It was recommended that at least 50 % of the fi stulas created was autogenous 2,11 .A summary of the observations of both access types in the U.S. shows that both fi stula types have a comparable operating duration, with the advantage of autogenous fi stulas being the lower number of post-maturity complications and fi stula interventions.Maintaining the graft operable requires a higher number of procedures such as angioplasty, thrombectomy and surgical revision.Grafts also demonstrate a higher occurrence rate of infectious complications.The creation of the autogenous AV fi stula is associated with early post-insertion complications and the necessary maturation of the fi stula.Its subsequent operation is typically of a long-term nature with a low complication rate 8,12,13 .This opinion can be agreed with.It should be mentioned that the autogenous fi stula has always been considered the gold standard in Europe.
The age of patient included in the chronic dialysis programme is increasing and so is mainly the number of patients with atherosclerotic and diabetic complications.The creation of the AV fi stula at the wrist level is often impossible in such patients.This is due to the sclerotic arterial bed of the forearm, often combined with a poor subcutaneous venous bed.The method of choice in the creation of the autogenous arteriovenous fi stula is the elbow fi stula, which involves arterialisation of the subcutaneous venous bed of the basilic or cephalic veins in the arm by means of anastomosis to the brachial artery.The autogenous elbow fi stula is currently the access used for the creation of up to 45 % of primary autogenous fi stulas for haemodialysis in Europe.Its creation is technically easy but it is necessary to consider all possible complications which make it diffi cult or prevent its application and which require further surgical procedures.In terms of utility and complication occurrence, the results are very good [13][14][15][16][17] .This fi stula type involves well-known disadvantages and complications.Arterialisation of the basilic vein is often accompanied by concurrent or subsequent basilic vein anteposition because, in its physiological course, it is placed subfascially in the proximal 2/3 of the arm 16,18 .The adverse complication of these fi stula types is the possible gradual development of the steal syndrome with upper extremity ischemia.
Despite great care in the creation of arteriovenous anastomosis of the fi stula within the diameter of 7 mm, there is always the risk of development of a hyperfunctional fi stula with steal syndrome and hand ischemia 19 .Under suitable anatomical conditions, the prevention can involve performance of elbow fi stula more distally on the radial or ulnar artery just under the brachial artery branching using the v. mediana antebrachii 20 .U.S. literature recognises the steal syndrome and deals with it mainly in fi stulas performed using the ePTFE graft 21,22 .The steal syndrome shows early manifestations in fi stulas performed with a graft as opposed to their later manifestation in autogenous fi stulas in connection with fi stula development 23 .
Diabetes mellitus is considered a risk factor for the occurrence of this complication 11,16,[24][25][26][27][28] .However, some authors do not agree 29 .Other risk factors include the use of brachial artery 30,31 , age over 60 30 , female gender 26,31 and lupus 26 .In terms of the steal syndrome occurrence, the brachiocephalic fi stula is a risk factor as opposed to the radiocephalic fi stula or to the application of the loop using a vascular prosthesis 24 .In advanced ischemic symptoms with fi nger gangrene, the basic factor is the atherosclerosis 26,27 .Since providing access for haemodialysis is a priority, the performance of the fi stula in the elbow is preferred in diabetic patients to the radiocephalic forearm fi stula, which is patent yet unsuitable for cannulation 17 .
The actual occurrence of the steal syndrome demonstrations after elbow fistula performance between the brachial artery and the cephalic or basilic veins is diffi cult to assess because published reports usually do not specify the performance type with regard to fi stula complications 14,32,33 .The steal syndrome fi stula has an asymptomatic form, the so-called "physiological steal" which occurs in 80 % of the patients, and a symptomatic form.The physiological steal is a demonstrable drop in blood pressure at the periphery and is compensated by the arterial collateral circulation and vasodilation.If these mechanisms fail, the symptomatic form occurs in 3.7-8 % of the fi stulas 14,19,25,30,34 .In the brachiocephalic and brachiobasilic fi stulas it even appears in as much as 10-25 % 19 .Its manifestations include cold sensation and pallor of the limb, pain while working or during dialysis, sensitivity loss, cramps and pain while resting, the development of ulcers, necrosis to tissue loss 19,23 .In certain cases, the problems are not caused by the steal syndrome but rather by ischemic monomelic neuropathy 35,36 .
It is a question how to examine a patient with a sclerotic arterial bed and diabetes prior to the autogenous fi stula performance in order to correctly indicate elbow fi stula and how to prevent the development of a hyperfunctional fi stula with the steal syndrome.There is probably no imaging method to indicate the fi stula type.There is also no demonstrable method to clearly determine, before or after the fi stula performance, that the fi stula will be hyperfunctional with steal demonstrations 34,37 .However, imaging can determine where the fi stula should not to be attempted because the arterial or venous bed does not provide a solid basis for a satisfactory result.After creation of the fi stula in elbow, it is necessary to monitor the patient and the fi stula as well as any steal syndrome symptoms development.
It is not diffi cult to recognise the developed clinical manifestations of the steal syndrome after the AV fi stula creation.Eff ort should mainly be made to recognise the early manifestations in order to treat the fi stula in time.A number of methods are recommended: physical examination of the site 24 , digital plethysmography of the arm periphery 24,25,33 , skin temperature monitoring 24 , periphery oxygenation measurement 24 , digital pressure measurements 37 , vessel bundle fl ow rate assessment by colour duplex sonography 33 or arteriography of the entire fi stula bed with or without fi stula compression 25,33 .The fi stula fl ow rate, however, does not typically infl uence steal development.Its occurrence rather depends on the peripheral arterial bed and collateral circulation 24,40 .Autogenous arteriovenous elbow fi stula for haemodialysis and upper extremity ischemia The main therapy principle is resolving the ischemia and maintaining the access.However, this principle may be diffi cult to fulfi l, mainly in risk groups of patients.A number of methods have been described and evaluated regarding modifi cation of the autogenous elbow fi stula between the brachial artery and the subcutaneous upper extremity (arm) venous bed with steal manifestations and regarding the maintained functionality thereof.
Primarily, it is the procedure of distal revascularization-interval ligation (DRIL).In principle, this is a venous bypass from the brachial artery above the AV fi stula anastomosis to the radial or ulnar artery with the subsequent ligation of the brachial artery below the AV anastomosis.The method was described by Schanzer 39 and applied by other authors who describe positive results, i.e. the ischemic symptoms improved in 90-100 % while maintaining fi stula patency in 80-100 % 22,25,33 .In patients with a poor arterial bed in the elbow, the anastomosis on radial or ulnar artery may be technically impossible.
Another technique is the proximalisation of the arterial infl ow.The principle of this method is to interrupt the AV fi stula anastomosis, treat the venous stump and then insert the ePTFE graft subcutaneously between the axillary artery and the original vein over the elbow.A 4-5mm gauge prosthesis is used.Larger-lumen prostheses can be later used for cannulation.Compared with the DRIL procedure, the stem artery is not ligated.The problems receded 90 % of cases, and the fi stula operability at 1 year was 90 %(ref. 32).
In line with the contemporary literature, other methods can be considered obsolete.These include reducing the fl ow through the fi stula by stitches, banding or clip 33,41 .The disadvantage of such methods is either an insuffi cient reduction of the fl ow and thus failure to remove steal or such a reduction of the fl ow as to cause thrombosis of the fi stula.Another option is the insertion of a graft after the AV anastomosis disconnecting between the brachial artery and eff erent vein in the forearm subcutis 38 .
In a number of instances, mainly in diabetic patients with severe ischemic changes in the extremity peripheries, the request for saving the fi stula cannot be met, and the only possibility is ligation of the arteriovenous access.In such cases, it must be determined whether to attempt another fi stula or to apt for placing long-term central vein catheters or ports.

CONCLUSIONS
It can be summarised that the autogenous fi stula in the elbow between the brachial artery and the cephalic or basilic vein currently holds an irreplaceable position in providing access for haemodialysis and that it needs to be preferred to using a graft.Mainly in risk groups of patients (diabetes mellitus, advanced stages of atherosclerosis), the condition of the patients needs to be monitored, as well as the fl ow through the fi stula due to the possible steal syndrome occurrence.Further fi stula treatment must be provided in the event of steal syndrome manifestations.
Proximalisation of the arterial infl ow appears to be the most suitable method.Another method is the DRIL procedure.Certain cases cannot be repaired, the fi stula cannot be saved and has to be surgicaly closed.