Study Of Sites Of Arterio-Venous Fistula In Dialysis Dependent Patients In A Tertiary Care Hospital.

Chronic kidney disease (CKD) is an important global health problem and is associated with substantial morbidity, mortality, and healthcare expenditure. With progressive deterioration of renal function, some patients eventually develop end-stage kidney disease (ESKD), requiring renal replacement therapy in the form of haemodialysis, peritoneal dialysis, or kidney transplantation. Among these modalities, haemodialysis remains one of the most widely used methods of renal replacement therapy. Effective and reliable vascular access is essential for adequate haemodialysis because it provides repeated access to the circulation for blood withdrawal and return during each dialysis session.

Therefore, the selection, creation, maturation, and long-term maintenance of vascular access are important components of the management of dialysis-dependent patients. The arterio-venous fistula (AVF) remains the preferred and generally considered the ideal vascular access for patients undergoing maintenance haemodialysis because it provides high blood flow, has greater durability, and is associated with lower rates of infection and thrombosis compared with synthetic grafts and central venous catheters [1]. An AVF is a surgically created vascular connection between an artery and an adjacent vein. Following creation, the increased arterial pressure and blood flow through the vein produce progressive venous arterialization, including dilatation and thickening of the venous wall.

This process, known as fistula maturation, allows the vein to withstand repeated needle cannulation and provide adequate blood flow for haemodialysis. The upper limb is generally preferred for AVF creation because it offers several accessible vascular sites and permits preservation of other vessels for future access procedures. The major types of upper-limb AVF include radiocephalic, brachiocephalic, and brachiobasilic fistulas. A radiocephalic fistula is usually created distally, commonly between the radial artery and cephalic vein at the wrist or anatomical snuff-box region. It is generally considered the preferred first option when suitable vessels are available because it preserves more proximal sites for future vascular access. When a distal fistula is not feasible because of inadequate vessel calibre, previous access failure, thrombosis, or other anatomical factors, a brachiocephalic fistula may be created at the elbow between the brachial artery and cephalic vein. A brachiobasilic fistula represents another proximal option and may require superficialization or transposition of the basilic vein to facilitate cannulation [2]. The choice of AVF site is therefore an important clinical decision. The principle of preserving the most distal suitable vascular site before progressing proximally is widely accepted because repeated vascular access procedures can progressively exhaust available vessels.

Distal, mid-forearm, and proximal forearm sites may be considered according to the patient's vascular anatomy and the condition of the artery and vein. Patient-related factors such as advanced age, diabetes mellitus, hypertension, peripheral vascular disease, cardiovascular disease, previous vascular access, and poor vessel quality may influence both the choice of access site and subsequent fistula maturation [3]. Although AVF is associated with better long-term outcomes than catheter-based vascular access, its creation does not guarantee successful maturation or prolonged patency. Failure of maturation, thrombosis, stenosis, infection, aneurysmal dilatation, and inadequate blood flow may compromise the effectiveness of the fistula. Reported AVF patency varies according to the type and location of the fistula, patient characteristics, surgical technique, and duration of follow-up. Several studies have reported first-year patency rates in the range of approximately 60–70%, with progressive reduction in patency during subsequent years [4].

Age is an important factor associated with vascular access outcomes. With increasing age, structural and functional changes occur within the arterial and venous systems. Atherosclerosis, arterial calcification, endothelial dysfunction, reduced vascular elasticity, and increased prevalence of comorbidities may adversely affect AVF maturation and long-term patency. Stenotic complications related to vascular access may consequently become more frequent in older dialysis-dependent patients [5]. In addition, the underlying disease responsible for CKD may contribute to vascular abnormalities even before AVF creation. Diabetes, hypertension, atherosclerotic disease, and other systemic disorders can produce pre-existing morphological and functional changes in blood vessels, potentially contributing to subsequent AVF insufficiency [6].

Preoperative assessment of the vascular system is therefore an important component of successful AVF planning. Clinical examination can provide information regarding arterial pulses, venous continuity, vessel size, previous scars, and collateral circulation. Where indicated, vascular mapping using Doppler ultrasonography can provide additional information regarding arterial diameter, venous calibre, vessel patency, and the presence of stenosis or thrombosis. Appropriate assessment and selection of the vascular site may increase the likelihood of successful maturation and help preserve future access options [7]. To study the distribution of sites of arterio-venous fistula creation among dialysis-dependent patients in a tertiary care hospital.

As per Nakagawa Y et al, dysfunction and thrombosis of arterio-venous fistulas due to insufficient blood flow were the most common causes of complications in patients undergoing haemodialysis [8]. Inadequate blood flow through the vascular access can compromise the efficiency of haemodialysis and may ultimately result in access dysfunction or failure. The development of thrombosis and other flow-related abnormalities may therefore have an important impact on the longevity and functional usability of an arterio-venous fistula. Early identification of access dysfunction and appropriate intervention are essential to maintain adequate vascular access and prevent the need for repeated access procedures. In Eastern India, Gupta S et al did one study among patients of End Stage Renal Disease requiring long term vascular access for haemodialysis and concluded that radio-cephalic arteriovenous fistula remains the procedure of choice [9].

The preference for radio-cephalic fistula is consistent with the principle of using the most distal suitable vascular site initially, thereby preserving more proximal vessels for the creation of future vascular access if required. Radio-cephalic AVF also provides a relatively straightforward surgical option when suitable arterial and venous anatomy is present. However, successful fistula maturation depends on several patient-related, vascular, and clinical factors. Basit A et al did one study including burst arterio-venous fistula during the time period of six months and concluded its significant association with patients’ age and type of cannulation [10]. Their findings emphasize that patient-related characteristics and the technique used for fistula cannulation can influence vascular access-related complications. Repeated cannulation of a fistula is necessary for maintenance haemodialysis, and inappropriate cannulation techniques may contribute to vascular wall injury, bleeding, aneurysmal changes, or other access-related problems. Therefore, careful patient selection, appropriate cannulation practices, and regular monitoring of the fistula are important for maintaining its functional integrity. Pogula VR et al did a longitudinal observational study among patients with brachio-cephalic fistulas and found that majority patients were 51-70 years of age undergoing failure of fistula on 30 days follow up [11].

This finding highlights the influence of age on vascular access outcomes, particularly among patients undergoing proximal AVF procedures. Older patients frequently have associated vascular and systemic comorbidities that may affect arterial and venous quality, fistula maturation, and long-term patency. Consequently, age and the underlying vascular status should be considered during preoperative assessment and selection of the appropriate AVF site. As per Sahasrabudhe P et al, average blood urea and creatinine values are significantly lesser in patients undergoing haemodialysis through successful mature fistulas as compared to patients with failed fistulas [12]. This observation demonstrates the importance of a functional and mature AVF in providing effective haemodialysis. A successful fistula allows adequate blood flow during dialysis and facilitates efficient clearance of uremic waste products. Conversely, fistula failure may result in inadequate dialysis, necessitating alternative vascular access and potentially increasing morbidity. These findings collectively emphasize the importance of appropriate AVF site selection, successful maturation, regular monitoring, and prevention of access-related complications among dialysis-dependent patients.

Radio-cephalic AVF remains an important and preferred vascular access option for maintenance haemodialysis in patients with end-stage renal disease. However, elderly patients may have a greater risk of delayed maturation or fistula failure because of underlying vascular disease, atherosclerosis, arterial calcification, and associated comorbidities. Despite these challenges, a successfully matured radio-cephalic fistula provides durable and effective vascular access with the advantage of preserving more proximal sites for future access creation. Therefore, careful preoperative vascular assessment, appropriate patient selection, meticulous surgical technique, and regular postoperative surveillance are essential to improve maturation and long-term patency. Early identification and management of stenosis or other access-related complications can further enhance fistula survival and ensure adequate haemodialysis.