Dr. Aurangzaib Khawaja
Specialty Doctor in Vascular Access & Renal Surgery, University Hospitals Birmingham
A new approach to dialysis access is a big step forward in the care of kidney patients.
To enable patients to undergo kidney dialysis – where machinery cleanses their blood three times a week – surgeons create a fistula, an ‘abnormal’ connection between two veins in the arm to facilitate the process.
The fistula joint, which enables blood to flow through at higher-than-normal speed, has traditionally been conducted by a surgical procedure.
But more recently, a minimally invasive technique known as Endo AVF (endovascular arteriovenous fistula) has shown a number of advantages that can be more comfortable for the patient, with fewer adverse reactions.
Dr. Zaib Khawaja, Specialty Doctor in Vascular Access & Renal Transplantation at the Queen Elizabeth Hospital, which is part of University Hospitals Birmingham, explains the system is for end stage kidney disease (ESKD) undergoing haemodialysis (blood dialysis).
Haemodialysis requires vascular access to connect a patient’s blood circulation to the dialysis machine via an arteriovenous fistula (AVF). It is generally created under local or regional anaesthetic to facilitate the four-hour dialysis sessions that take place three times a week in a hospital setting.
“For the last 60 years this has been done with an operation where a cut is made to find those blood vessels and stitch them together,” he says. “That has remained very much unchanged, but it has its challenges.”
Up to 40% of patients may not respond well to the surgical procedure, and it could take up to three months for the joint to develop.
But since 2016, the Birmingham unit has been using the Becton Dickinson WavelinQ™ EndoAVF system, which creates an endovascular AV fistula (Endo AVF) for haemodialysis access, a minimally invasive technique performed under radiological guidance.
“It is a less invasive way of making the fistula and there is no scarring after the procedure,” he says.
Other benefits of Endo AVF are that it can increase possible options for the fistula site from three to five and avoids the risk of scar infection or disfigurement from the traditional fistula where lumps can appear early across the arm. It can also reduce the number of hospital visits for fistula maintenance.
“By making these percutaneous or radiologically-guided fistulas we create a softer but equally effective fistula, which distributes the stress on the vein,” he says.
Patients on dialysis are already fatigued with the three-times-a-week visits. We have to do whatever we can to minimise this and give them a fistula that is less disfiguring and works well.
Patients referred for fistula are anatomically assessed for the next stage of their kidney treatment care, which may be for Endo AVF and while some patients may request it, Dr Khawaja emphasises that the process is a team effort involving the nephrologist, radiologist, surgeon and dialysis nurse.
“But whatever we do, it has to have a focus on patient and their dialysis nurse because they have to have a working fistula that can easily have a needle put in,” he says.
The fistula procedure takes about 40 minutes and is not dependent on access to an operating theatre. Indeed, in the United States and Europe it is being performed outside of hospital settings, which is proving of value during the COVID-19 pandemic.
Big step forward
The crux of the procedure is in making a communication between two blood vessels. Endo AVF is a dual catheter system with two magnetic arrays. Dye tests map the vessels and then the cross wire is advanced through the needles to the selected fistula site, with the magnets precisely aligning the two adjacent vessels. A radio frequency pulse is discharged to create a connection between the artery and vein.
Dr Khawaja describes the technology as the biggest advance in this area for six decades. “Even now with surgical fistula creation, three or four out of 10 patients will need more operations or interventions, so a technology that can potentially reduce that by 20-30% is a big step forward,” he continues.
“Patients on dialysis are already fatigued with the three-times-a-week visits. We have to do whatever we can to minimise this and give them a fistula that is less disfiguring and works well.”