Abstract
Balloon-assisted maturation (BAM) of arteriovenous fistulas has conventionally been performed via direct fistula access. The transradial approach has not been well described for BAM, although its use has been reported throughout the cardiology literature. The purpose of the present study was to assess the outcomes of transradial access for its use with BAM. A retrospective review of 205 patients with transradial access for BAM was performed. One sheath was inserted into the radial artery distal to the anastomosis. We have described the procedural details, complications, and outcomes. The procedure was considered technically successful if transradial access had been established and the AVF had been ballooned with at least one balloon without major complications. The procedure was considered clinically successful if no further interventions had been required for AVF maturation. The average time for BAM via transradial access was 35 ± 20 minutes, with 31 ± 17 mL of contrast used. No access-related perioperative complications, including access site hematoma, symptomatic radial artery occlusion, or fistula thrombosis, had occurred. The technical success rate was 100%, and the rate of clinical success was 78%, with 45 patients requiring additional procedures to achieve maturation. Transradial access is an efficient alternative to trans-fistula access for BAM. It is technically easier and allows for better visualization of the anastomosis.
Keywords: Arteriovenous fistula maturation, Balloon-assisted maturation, Transradial access
An autogenous arteriovenous fistula (AVF) is often the preferred hemodialysis (HD) access for patients with end-stage renal disease.1 Primary AVF maturation can frequently be hampered by multiple factors, including small vein diameters, the presence of stenosis, and multiple stealing branch vessels. More than 60% of AVFs will require intervention to achieve maturation, and balloon-assisted maturation (BAM) has been the most commonly used technique to promote AVF maturation.2 It involves balloon angioplasty of the entire usable segment of the AVF, including the perianastomotic segment.
Conventionally, BAM has been performed via trans-fistula access. This technique requires additional steps compared with transradial access, including compression of the venous limb to visualize the arteriovenous anastomosis and both antegrade and retrograde access to allow for treatment of the entire length of the AVF.
Recently, transradial access has been explored for BAM.3, 4, 5 This approach allows for better visualization of the AVF because venous compression is not required and avoids the need for multiple access sites. Transradial access has been well described in the interventional cardiovascular literature and is the preferred access site for percutaneous coronary intervention and diagnostic angiography according to the 2018 European Society of Cardiology and European Association for Cardio-Thoracic Surgery guidelines.6,7 However, transradial access has not been extensively evaluated for BAM. The current literature suggests that transradial access could result in complications such as arterial perforation, spasm, and/or occlusion.8,9 The purpose of the present study was to assess the outcomes of transradial access for its use with BAM.
Methods
Study design
We conducted a retrospective review of a prospectively maintained database containing patients who had undergone BAM via transradial access. All the patients were treated by a single vascular surgeon between 2015 and 2021 at a tertiary academic medical center. The Northwell Health institutional review board determined the present study to be minimal risk research and waived the requirement for patient informed consent. The patient demographics, fistula type, procedural characteristics, and periprocedural complications and outcomes were entered into the database. Race and sex data were collected by self-report using prespecified fixed categories. Patients who had undergone diagnostic fistulography or procedures to maintain patency of already matured AVFs were excluded from analysis. These exclusionary criteria were established to control for potential confounding variables associated with diagnostic fistulography, management of central venous stenosis, or focal fistula stenosis in failing AVFs, rather than long-segment angioplasty often performed during BAM.
Our protocol has been to assess AVF maturation at ∼6 weeks after AVF creation, which consists of a physical examination and duplex ultrasound examination. Previously described ultrasound criteria were used to determine whether the AVF is ready for use or intervention would be necessary. The indication for BAM included a vein diameter <6 mm, the presence of focal AVF stenosis, a volume flow of <675 mL/min, and/or the presence of stealing branch vessels.10 The time to BAM was defined as the number of days between AVF creation and the first BAM.
Balloon-assisted maturation
BAM was performed with local anesthesia under fluoroscopic guidance in an outpatient setting using transradial access. Before the procedure, adequate collateral perfusion to the hand was assessed using an Allen test or a modified Allen test with pulse oximetry. Radial artery patency and caliber, the presence of atherosclerosis, and calcification were evaluated by the surgeon using duplex ultrasound at the start of the procedure. Transradial access was our first-line approach for all BAMs, and only patients without adequate collateral ulnar circulation to the hand or whose radial artery was stenotic or heavily calcified underwent BAM via trans-fistula access. The latter patients were not included in this cohort.
A 6F Prelude radial sheath (Merit Medical Systems) was inserted into the radial artery distal to the anastomosis under ultrasound guidance (Fig 1). After cannulation, 2.5 mg of verapamil was routinely delivered via the sheath into the radial artery to prevent vasospasm. In contrast, for the trans-fistula approach, we accessed the AVF antegrade with a 6F Prelude radial sheath (Merit Medical Systems) just proximal to the anastomosis. A second 6F sheath was placed in the distal aspect of the fistula in a retrograde fashion (Fig 2). Our preference has been to use a 6F sheath because it allows us to use large angioplasty balloons (≥8 mm), as needed.
Fig 1.
A, Transradial access for balloon-assisted maturation (BAM) with a 5F radial sheath. The location of the incision used to create the radiocephalic arteriovenous fistula (AVF) is marked. B, Fistulogram via transradial access demonstrating the working length between the access site at the wrist to the anastomosis of a radiocephalic AVF. Perianastomotic stenosis was easily visualized and treated with balloon angioplasty.
Fig 2.
Trans-fistula approach for balloon-assisted maturation (BAM) with an antegrade and a retrograde 6F Prelude radial sheath inserted into an arteriovenous fistula (AVF).
After cannulation of the radial artery, serial long-segment dilations of the vein were conducted using long (80-100 mm), 4- to 8-mm-diameter Mustang balloons (Boston Scientific; Fig 1, B). The initial balloon size was chosen to be 1- to 2-mm larger than the vein caliber estimated on the initial fistulogram with the intention to dilate the AVF to ∼6 mm in diameter. The entire length of the vein that could be used for cannulation was ballooned with full insufflation at 2.5 to 3.0 mPa for 120 seconds. Angioplasty was performed starting from the distal fistula (toward the central outflow), followed by the proximal fistula (toward the arterial anastomosis). Serial ballooning was aborted if contrast extravasation was seen on fistulography. Coiling of large branches was performed if they were ≥3 mm in diameter and had a persistent high-velocity flow on imaging after angioplasty of the AVF.
At the end of the procedures performed via a transradial approach, hemostasis was achieved by applying the Vasc Band Hemostat (Teleflex) for 1 hour (Fig 3). Periprocedural access-related complications included access site hematoma, symptomatic radial artery thrombosis, and AVF thrombosis. Complications were reported by the operating surgeon based on the physical examination findings. The procedure was considered technically successful if transradial access was established and the AVF had been ballooned with at least one balloon without the development of major complications. The procedure was considered clinically successful if no further interventions had been required for AVF maturation. An AVF was considered matured if it had been successfully used for HD with the prescribed flow rates for 4 weeks without the need for further intervention. The time to catheter-free HD was calculated as the number of days between AVF creation and catheter removal and between the first BAM and catheter removal.
Fig 3.
Hemostasis with a Vasc Band Hemostat after the transradial approach. Inflation of the Vasc Band Hemostat applies direct compression to the radial artery distal to the arteriovenous anastomosis.
Statistical analysis
Summary statistics (ie, mean ± standard deviation or median and interquartile range [IQR]) were calculated for the continuous variables and frequencies and proportions for the categorical variables. The ultrasound findings before BAM were compared with those after the BAM procedures and analyzed using a paired t test for normally distributed continuous dependent data and the sign test for non-normally distributed data. The McNemar test was used to analyze paired categorical variables. An observed P value of < .05 was considered statistically significant. All statistical analyses were performed using STATA, version 17, software (StataCorp).
Results
A total of 205 patients had undergone BAM via transradial access during the study period. Of these 205 patients, 60% were men, with an average age of 61 ± 12 years, and 41% were Asian. The demographics, comorbidities, and preprocedural details are summarized in Table I. Most the AVFs had been created on the left side (n = 146; 71%) and radiocephalic was the most common AVF type (n = 159; 76%). The mean diameter of the veins used for AVF creation was 2.4 ± 0.8 mm. Of the 205 patients, 31 (15%) had a history of previously failed AV access (graft or fistula). At BAM, 168 patients (82%) were undergoing dialysis via a tunneled catheter. The median time from AVF creation to BAM was 67 days (IQR, 54-93 days). Duplex ultrasound was performed to evaluate AVF maturation and revealed a mean vein diameter before BAM of 4.3 ± 1.2 mm, a median volume flow of 555 mL/min (IQR, 350-818 mL/min). In addition, 20% of the patients had focal vein stenosis (Table II).
Table I.
Demographics and fistula characteristics
| Demographics and fistula characteristics | Value |
|---|---|
| Patients | 205 (100) |
| Age, years | 61 ± 12 |
| Male sex | 123 (60) |
| Race | |
| Asian | 84 (41) |
| Black | 80 (39) |
| White | 35 (17) |
| Other/unknown | 6 (3) |
| Hispanic | 14 (7) |
| BMI, kg/m2 | 27 ± 7 |
| Hypertension | 185 (90) |
| Hyperlipidemia | 162 (79) |
| Diabetes | 160 (78) |
| Coronary artery disease | 80 (39) |
| Peripheral vascular disease | 16 (8) |
| COPD | 12 (6) |
| Atrial fibrillation | 27 (13) |
| Congestive heart failure | 37 (18) |
| AICD/pacemaker | 13 (6) |
| Smoking history | 31 (15) |
| History of failed HD access | 31 (15) |
| Ipsilateral | 10/31 (32) |
| Contralateral | 21/31 (68) |
| Left side AVF | 146 (71) |
| Preoperative vein diameter, mm | 2.4 ± 0.8 |
| Type of AVF | |
| Radiocephalic | 156 (76) |
| Brachiocephalic | 31 (15) |
| Brachiobasilic | 18 (9) |
| HD required at BAM | 168 (82) |
| Time to BAM, days | 67 (54-93) |
AICD, Automatic implantable cardioverter defibrillator; AVF, arteriovenous fistula; BMI, body mass index; BAM, balloon-assisted maturation; COPD, chronic obstructive pulmonary disease; HD, hemodialysis.
Data presented as number (%), mean ± standard deviation, or median (interquartile range).
Table II.
Duplex ultrasound findings
| Variable | Before BAM | After BAM | P value |
|---|---|---|---|
| Vein diameter, mm | 4.3 ± 1.2 | 5.4 ± 1.4 | < .0001 |
| Volume flow, mL/min | 556 (350-818) | 720 (537-938) | .0004 |
| Veins stenosis | 41 (20) | 14 (7) | .0001 |
| Presence of large branch vessels | 12 (6) | 6 (3) | .165 |
BAM, Balloon-assisted maturation.
Data presented as mean ± standard deviation, median (interquartile range), or number (%).
The average procedure time, fluoroscopy time, and contrast used was 35 ± 20 minutes, 5 ± 4 minutes, and 31 ± 17 mL, respectively. Most of the AVFs (95%) had been ballooned with ≥6-mm balloons. For the remaining patients, ballooning had been aborted because of contrast extravasation from the AVF after using small, 4- to 5-mm, balloons. Contrast extravasation was successfully managed with manual compression alone without the need for further intervention. No access-related periprocedural complications occurred in this group, including access site hematoma, AVF thrombosis, or symptomatic radial artery thrombosis. The technical success rate was 100%, and the clinical success rate was 78%, with 45 patients requiring additional procedures to achieve maturation. The median time to catheter-free HD was 104 days (IQR, 85-140 days) after AVF creation and 33 days (IQR, 23-57 days) after the first BAM procedure (Table III). Another measure of procedural success was the post-BAM duplex ultrasound findings, which showed a significant increase in the vein diameter and volume flow and a decreased incidence of vein stenosis compared with the pre-BAM duplex ultrasound findings (Table II).
Table III.
Procedural details, complications, and outcomes (n = 205)
| Characteristic | Value |
|---|---|
| Procedure duration, minutes | 35 ± 20 |
| Fluoroscopy time, minutes | 5 ± 4 |
| Contrast used, mL | 31 ± 17 |
| Largest diameter balloon used, mm | |
| 8 | 133 (65) |
| 7 | 37 (18) |
| 6 | 25 (12) |
| 5 | 6 (3) |
| 4 | 4 (2) |
| Coiling of branch vessels | 21 (10) |
| Technical success | 205 (100) |
| Access site hematoma | 0 (0) |
| Contrast extravasation | 34 (17) |
| Symptomatic radial artery thrombosis | 0 (0) |
| Periprocedural AVF thrombosis | 0 (0) |
| Maturation rate | 192 (94) |
| Need for additional BAMs | 45 (22) |
| Time to catheter-free HD, days | |
| After AVF creation | 104 (85-140) |
| After first BAM | 33 (23-57) |
AVF, Arteriovenous fistula; BAM, balloon-assisted maturation; HD, hemodialysis.
Data presented mean ± standard deviation, number (%), or median (interquartile range).
Discussion
Endovascular treatment of nonmaturing AVFs has conventionally been performed via trans-fistula access.4,5,11,12 Our study has demonstrated that transradial access for BAM can be a practical alternative with a short procedural time, low rate of complications, and excellent technical and clinical success rates.
Transradial access has been established as a safe approach in interventional cardiology and has been shown to result in fewer access site complications than the transfemoral approach.13 Transradial access has been associated with low rates of non–limb-threatening radial artery thrombosis.5 In our study, none of the patients who had undergone transradial access for BAM had experienced periprocedural complications, including access site hematoma, AVF thrombosis, and symptomatic radial artery thrombosis.
Transradial access is a technically easier procedure that uses a single sheath, instead of the antegrade and retrograde sheaths required for the trans-fistula approach. Transradial access might, thus, be more time efficient and ergonomic for the operator. Furthermore, during trans-fistula access, the operator's hands could have increased exposure to the primary radiation beam when working through the retrograde sheath (Fig 4). The overall radiation exposure during percutaneous procedures to the operator is relatively low; however, the radiation doses to the operator's limbs closest to the radiation beam will be higher.14 Hand positioning for transradial access can limit radiation exposure to the operator's hands, because it requires the use of only one sheath, which is positioned outside the radiation beam (Fig 5).
Fig 4.
Set up for fistulography via the trans-fistula access demonstrating the C-arm centered over the retrograde sheath to image the arteriovenous fistula (AVF) and the operator's hands directly beneath the primary radiation beam when accessing the retrograde sheath.
Fig 5.
Fistulogram via the transradial approach. The C-arm is centered over the arteriovenous fistula (AVF), with the radial sheath outside the radiation beam. The operator's hands remain outside the primary radiation beam when accessing the radial sheath.
Transradial access could also be optimal for the small caliber veins often seen during BAM. Accessing immature veins directly can lead to AVF thrombosis because the sheath could be occlusive to flow throughout the entire procedure. In our series, AVF thrombosis was not observed.
Transradial access can be used for all upper extremity dialysis access types. Given all the advantages we have seen and limited disadvantages with this method, we “plan-to-BAM” by creating our radiocephalic anastomosis proximal enough to leave room for transradial access distal to the anastomosis (Fig 1). However, other surgeons might create more distal anastomoses, including snuffbox AVFs, limiting their ability to access the radial artery for BAM. Transradial access is not indicated for patients with upper arm AVFs and a high takeoff of their radial artery. Up to 14% of patients will have a high radial takeoff from the brachial or axillary artery.15
Transradial access for interventions to maintain patency of already matured AVFs might not be as advantageous. Matured AVFs are often large and the risk of vein thrombosis using trans-fistula access is minimal. The presence of focal AVF stenosis is more common in these patients, and long-segment dilatation of veins is rarely needed. Transradial access is ideal for AVFs failing because of perianastomotic stenosis because this location is more difficult to address via trans-fistula access. Transradial access for BAM allows for better visualization of the anastomosis and technically simple ballooning (Fig 1, B). Furthermore, transradial access might have limited use in cases of central venous stenosis, which could require large diameter balloons and stents. A major limitation of transradial access in these cases is the sheath size (6F), which could preclude the use of balloons >10 mm.
Inherently, one limitation of the present study was its retrospective cohort design and the relatively small sample size. Some of the data were not available for our analysis, such as pre-BAM radial artery diameters, which could be an important factor contributing to the success of this procedure. Routine ultrasound evaluations were not performed postoperatively to evaluate the patency of the radial artery unless the patient had developed symptoms. Therefore, we were unable to quantify the number of asymptomatic radial artery thromboses and might have underestimated the true incidence of this adverse event. Additionally, to remove potential confounding variables, all the procedures had been performed by a single vascular surgeon. However, it is possible this introduced a procedural bias limiting the generalizability of the results. The procedure time and amount of contrast used might have demonstrated greater variability if more vascular surgeons had been included in the present study. A randomized controlled trial to compare transradial access with trans-fistula access for BAM in patients who qualify for both approaches would be necessary to fully access the benefits of this technique.
Conclusions
The results of our study have shown that transradial access for BAM is an efficient and effective alternative to direct AVF access. It might also improve the ergonomics and decrease the radiation exposure to the operator's hands. Transradial access could offer a less expensive alternative by decreasing the number of sheaths used during BAM.
From the Society for Clinical Vascular Surgery
Footnotes
Author conflict of interest: none.
The editors and reviewers of this article have no relevant financial relationships to disclose per the Journal policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest.
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