Why does dialysis need a “good vessel”?
When kidney function fails severely (end-stage kidney disease), patients need regular hemodialysis. To make dialysis safe and effective, a “lifeline” with sufficient blood flow that can be needled repeatedly is required: the arteriovenous fistula (AVF).
A conventional AVF is created surgically: the skin of the arm is incised and an artery and a vein are sutured together.
Modern AVF techniques now include the “percutaneous (endovascular) arteriovenous fistula” (EndoAVF, also called pAVF), a minimally invasive alternative that replaces the surgical skin incision with a needle puncture, reducing surgical trauma. (Not yet in use in Taiwan at present.)
How EndoAVF / pAVF works: connecting the vessels without sutures
The ingenious feature of the percutaneous AVF is that a thin catheter is advanced into the blood vessel through a needle puncture, much like cardiac catheterization, and the artery and vein are connected without any surgical suture.
The core of the technique is creating a permanent communication between an artery and a vein directly through the vessel wall, under precise ultrasound and X-ray guidance.
There are currently two main systems:
| System | Puncture site | Connection mechanism | Location of the fistula | |
| Ellipsys™ | 1 | A single venous puncture | A catheter delivers thermal energy that instantly fuses the two vessels to form the anastomosis. | Created between the proximal radial artery and the perforating vein. |
| WavelinQ™ | 2 | Usually requires two punctures: one arterial and one venous. | Radiofrequency (RF) energy is used to create a connecting channel through the vessel walls. | Created between the ulnar artery / radial artery and its accompanying vein. |
Both techniques follow the principle of placing the fistula “as distally as possible”: the fistula is preferably created at the wrist or distal forearm, so that more healthy vessels in the arm are preserved for future use.
Ellipsys system (excerpted from the Medtronic YouTube channel)
WavelinQ system (excerpted from the BD YouTube channel)
Practical benefits of EndoAVF / pAVF and the clinical data behind them
Compared with conventional surgery, EndoAVF / pAVF involves a smaller wound and faster recovery, and also offers some clinical advantages:
- Lower risk of complications: According to clinical studies, this minimally invasive approach may reduce the risks of high-output heart failure, aneurysm at the cannulation sites and cephalic arch stenosis that can occur with conventional surgery.
- Durable long-term performance: One report on the Ellipsys system describes a five-year cumulative patency of up to 82.0%, and early data suggest that the results of EndoAVF / pAVF are comparable to those of surgical AVFs.
Multidisciplinary teamwork improves the chance of success
Success with EndoAVF / pAVF does not depend on a single physician. The technique requires a complete program and the support of a multidisciplinary team, including:
- Precise pre-operative assessment: Before creating a fistula, the physician must perform comprehensive vessel mapping with ultrasound to plan the most suitable access blueprint.
- Anaesthesia and comfort: A brachial plexus block can be used to keep the patient comfortable during surgery and to help the vessels dilate afterwards.
- Operator experience: The operating physician needs dedicated simulation training and clinical mentoring, along with complete interventional radiology skills.
The minimally invasive procedure is only the first step to success. For the fistula to be truly usable for dialysis (called maturation), post-operative care and follow-up are also key:
- Structured follow-up: Physicians use structured ultrasound surveillance to check the fistula’s blood flow, diameter and depth regularly, to ensure that it meets the standard required for dialysis.
- Active “tuning” (adjunctive interventions): Many minimally invasive fistulas need active intervention after creation to be “tuned”, for example PTA balloon angioplasty to widen the arteriovenous junction. This is how a fistula is made ready for dialysis use.
The percutaneous arteriovenous fistula (EndoAVF / pAVF) is another way of creating dialysis vascular access, combining the advantages of a minimally invasive technique with a multidisciplinary post-operative follow-up process.
Sources:
1. Ellipsys™ Vascular Access System product manual (from the Medtronic product website)
2. Endovascular Arteriovenous Fistula Creation: A Review (from Seminars in Interventional Radiology)
3. A Society of Interventional Radiology Practice Guidance Document on Percutaneous Arteriovenous Fistulas for Dialysis Access (from the Journal of Vascular and Interventional Radiology)
Summary of JVIR Practice Guidance Statements
| Technique selection | 1. Create the fistula between the ulnar/radial artery and its accompanying vein. |
| Pre-operative preparation | 2. Perform comprehensive vessel mapping with ultrasound or angiography before surgery. |
| Program management | 3. Establish a flowchart to guide patient selection, the procedure and follow-up care. |
| Team and skills | 4. The operating physician must have solid experience and interventional radiology skills. |
| Team and skills | 5. A multidisciplinary team is needed, including a vascular access case manager. |
| Facility requirements | 6. Make sure the clinic and the procedure room have ultrasound and X-ray fluoroscopy equipment. |
| Post-operative care | 7. Establish a structured follow-up plan, including ultrasound and subsequent adjunctive interventions. |
| Technical principle | 8. A pAVF should be placed as distally as possible to preserve proximal access options. |
| Patient education | 9. The technical success rate of pAVF is high (>95%), but successful use for dialysis is not guaranteed. |
| Patient education | 10. Many pAVFs need one or more adjunctive interventions to mature. |
| Procedural support | 11. A brachial plexus block can be used to provide analgesia and vasodilation. |
| Procedural support | 12. Consider an axillary or supraclavicular brachial plexus block. |
| Procedural support | 13. Teams should understand the potential complications of brachial plexus blocks and be able to manage them. |
| Physician training | 14. Training should cover vascular anatomy, vessel mapping and procedural technique. |
| Physician training | 15. Simulation training should be included in the curriculum. |
| Physician training | 16. Mentoring of new operators by experienced physicians is recommended. |
| Procedure confirmation | 17. Use of image guidance (especially ultrasound) to confirm anastomotic patency is encouraged. |
| Complication management | 18. During the procedure, attention must be paid to preventing pseudoaneurysm formation. |
| Complication management | 19. Adjunctive intervention should be considered when acute arterial steal occurs. |
| Complication management | 20. Interventional treatment should be considered when the fistula develops significant stenosis or occlusion. |
| Post-operative care | 21. Appropriate anticoagulant/antiplatelet therapy is used to reduce the risk of thrombosis. |
| Post-operative follow-up | 22. Perform structured clinical/ultrasound follow-up and actively manage access-related problems. |
| Post-operative follow-up | 23. Before the first cannulation for dialysis, confirming fistula maturity with ultrasound is recommended. |
