Anil K. Agarwal @DrAnil001
Anil K. Agarwal is Professor of Medicine and Section Chief of Nephrology at Ohio State University Hospital East in Columbus, Ohio. He has published widely and edited the first textbook of Interventional Nephrology and NephSAP on Interventional Nephrology. He is a passionate clinician, educator, interventional nephrologist, and is the President of ASDIN.
Competitors for the HD Access Region
Choices in life represent options for individualization, but percutaneous or endovascular AVF (popularly known as pAVF or endo AVF) offers much more than just an option to the patients with end-stage kidney disease (ESKD). Perhaps it is the ‘sliced-bread’ of AVF creation, making it the most important advancement of nephrology in 2019!
It is indeed an exciting era in Nephrology, abounding with relentless innovations in the treatment of kidney disease. A young medical discipline, nephrology has been precocious in developing exciting new methods of replacing a vital end organ function by developing kidney transplantation and dialysis for patients with ESKD. Performance of maintenance hemodialysis (HD) mandated a sustainable vascular access, which led to the development of the Scribner shunt in 1960, though its utility quickly became questionable due to the complications of infection and thrombosis.
A surgically created arteriovenous fistula (AVF) emerged in 1966, invented by Brescia and Cimino, which remains the vascular access of choice for most. However, this AVF was created by open surgical anastomosis of the artery and vein and, over time, has shown biological and technological drawbacks. These include quite frequent early failure of maturation as well as the logistical dilemma of delay in its creation, due largely to its dependence on processes related to creation by open surgical method. These shortcomings of AVF have led to the development of alternate conduits (AV grafts) and dialysis catheters, which have problems of their own. A true advance in making AVF creation simpler has been sorely lacking over the past six decades, until now.
Excitement in percutaneous creation of AVF stems from two new technologies approved by FDA in 2019. One uses thermal energy and another uses radiofrequency to readily make arteriovenous anastomosis via an endovascular, non-surgical approach, in appropriately selected individuals, who either have failed distal AVF at wrist or are unsuitable for it. These percutaneous techniques to create endovascular AVF (endo AVF) represent a Himalayan accomplishment in making the process simpler and efficient for many spectacular reasons, which are worth noticing by all those who are involved in the care of patients on hemodialysis:
- The endo AVF utilizes veins in proximal forearm that are uncommonly punctured for other reasons, making them suitable for AVF creation if needed.
- These veins represent novel sites for AVF creation in the ‘proximal’ forearm (eg, ulnar artery to ulnar vein, radial artery to perforator vein, and many other potential combinations), affording additional sites which provide a choice of unusual real estate for AVF creation. This is a critical issue in a young patient with limited sites for AVF creation, as one can use these proximal forearm sites for endo AVF without having to move directly from wrist to upper arm for the next surgical AVF.
- Endo AVF can be created most of the time under local and/or regional anesthesia with conscious sedation. Avoidance of general anesthesia is extremely useful in patients with ESKD due to a high risk in these patients with multiple complex comorbidities.
- One of the endo AVF techniques does not require fluoroscopy for creation and uses ultrasound only, avoiding radiation exposure. However, if more interventions are required, fluoroscopy may be needed.
- There is no skin incision involved, which makes healing nearly a non-issue while keeping the forearm cosmetically aesthetic (often a concern for young individuals).
- In contrast to the surgical end-to-side AVF, these technologies create side-to-side AVF (joining sides of both artery and vein) that has favorable flow and shear stress profiles- possibly the reason for less delayed complications.
- Endo AVF has shown improved maturation rates and earlier cannulation as compared to surgical AVF, possibly related to the absence of surgical handling of vessels and sparing of the vasa vasorum and vasa nervorum.
- Endo AVF study results have shown reduced number of interventions and better patency (greater than 90% over 24 months) with reduced costs.
- As endo AVF use radial artery for inflow (not a larger brachial artery), there is less likelihood of development of high flow AVF, steal phenomenon, and aneurysms.
- Often, endo AVF may have more than one outflows that can be cannulated for dialysis. These outflows in upper arm can be used for future secondary AV fistula creation if the endo AVF in proximal forearm fails.
- Endo AVF can be created by multiple disciplines that perform endovascular interventions (interventional nephrology, radiology for Ellipsys technique; Interventional Radiology and surgery for Wavelinq technique in Pivotal trials) in outpatient centers. Thus, these techniques empower nephrologists and other physicians to create AVF.
- Endo AVF further expands choices. Depending upon suitable anatomy as assessed by duplex ultrasound, two different technologies exist which operators with different expertise can use for different sets of patients.
- Frequently, same day outpatient assessment and creation of endo AVF in outpatient center can sidestep the pre-surgical operating room scheduling issues (vessel mapping, surgical referral, surgical consultation, pre-surgical cardiac, anesthesia and laboratory evaluation, operating time availability, surgical follow-up). This evades the procedural delay in AVF creation and potentially reduces catheter exposure.
- There is a high level of patient satisfaction with endo AVF procedure.
Thus, a number of encouraging features of endo AVF represent a major advance over surgical AVF. However, it is important to note that surgical AVF is not obsolete and endo AVF simply provides a choice in terms of technique as well as additional optional sites for the creation of AVF.
Based on these attributes, there is no other such advance – not only in 2019 – but also throughout the last half century- that has influenced multiple important aspects of direct care while improving choice for patients with ESKD.
Yes, the concept of an encompassing life-plan to create a blueprint for renal replacement modality (kidney transplant, hemodialysis, or peritoneal dialysis), choice of location (treatment at home or in-center), and a dialysis access based on those decisions is a significant advance in the new KDOQI Vascular Access Guidelines. Getting the ‘right access in the right patient, at the right time, and for the right reason’ appropriately keeps the patient in front and center of the plan. However, the guidelines are still based upon suboptimal quality of evidence. Availability of novel technology, exemplified by the new ‘endo AVF’, will likely guide upcoming global guidelines and clinical practice.
– Guest Post written by Anil K. Agarwal @DrAnil001
As with all content on the AJKD Blog, the opinions expressed are those of the author of each post, and are not necessarily shared or endorsed by the AJKD Blog, AJKD, the National Kidney Foundation, Elsevier, or any other entity unless explicitly stated.