|Year : 2021 | Volume
| Issue : 6 | Page : 147-152
Prospective evaluation of radiocephalic arteriovenous fistula to determine the causes for non maturity with clinical and ultrasonography-doppler
Sameer Bhuwania, Rajesh Goel, Ravi Bansal, Sanjiv Saxena
Department of Nephrology, PSRI Hospital, New Delhi, India
|Date of Submission||08-Jan-2021|
|Date of Decision||12-Jun-2021|
|Date of Acceptance||02-Jul-2021|
|Date of Web Publication||20-Jan-2022|
Department of Nephrology, PSRI Hospital, New Delhi
Source of Support: None, Conflict of Interest: None
Introduction: The RC-AVF is the most important tool for hemodialysis considered to be the life line of patients. In our study, we have tried to find the incidence of AVF non maturation and the physical and ultrasonological parameter which can predict its non maturation. Materials and Methods: Radio-cephalic AVF surgery was done taking into account the inclusion and exclusion criteria with a follow up period of 6 weeks. The cases were evaluated pre-operatively and post-operatively using clinical and DUS. Results: 91 cases were studied with a success surgical outcome in 54.9% (50) of patients. The mean age of 46.04 yrs, male sex and less diabetes (46%) was associated with a matured RC-AVF surgical outcome. Mean preoperative artery diameter of > 0.21 ± 0.04 cm and vein diameter of > 0.20 ± 0.03 cm was seen in the matured cases. Incremental test and Resistive index was normal in 62% and 80% of the matured cases respectively, while calcification of feeding artery was associated with poor outcome. Further Clinical examination showed sensitivity 88% and specificity 95% whereas Doppler studies showed a sensitivity of 100% and specificity of 92.6% to successfully diagnose matured cases. Thrombosis (51%) was the most common cause of AVF failure followed by juxta anastomosis stenosis (14%). Conclusion: In this study we found that a thorough pre-operative evaluation of the vessels of RC-AVF can predict its maturation. Also a regular follow-up and use of clinical and imaging studies can help diagnose and timely salvage a failing AVF.
Keywords: Causes of AVF failure, Doppler study of arteriovenous fistula, preoperative evaluation of arteriovenous fistula, radiocephalic- arteriovenous fistula maturation
|How to cite this article:|
Bhuwania S, Goel R, Bansal R, Saxena S. Prospective evaluation of radiocephalic arteriovenous fistula to determine the causes for non maturity with clinical and ultrasonography-doppler. Indian J Vasc Endovasc Surg 2021;8, Suppl S2:147-52
|How to cite this URL:|
Bhuwania S, Goel R, Bansal R, Saxena S. Prospective evaluation of radiocephalic arteriovenous fistula to determine the causes for non maturity with clinical and ultrasonography-doppler. Indian J Vasc Endovasc Surg [serial online] 2021 [cited 2022 Jul 4];8, Suppl S2:147-52. Available from: https://www.indjvascsurg.org/text.asp?2021/8/6/147/336027
| Introduction|| |
The arteriovenous fistula (AVF) surgery has long been a life line for patients undergoing hemodialysis. Although initially, the surgery was done only for young and healthy patients, later eligibility was expanded for others too including diabetics and elderly. Being the most trusted and least morbid hemodialysis access, radio-cephalic AVF (RC-AVF) success is very important for healthy and adequate dialysis therapy. The care and functioning of AVF is of the utmost importance for any dialysis patient; therefore, in this study, we have tried to look into the various problems which can arise with maturation and functioning of RC-AVF.
We found out the incidence of nonmaturation of RC-AVF at our center at 6 weeks postoperatively. Moreover, we tried to know the causes of nonmaturation of RC-AVF and the relevance of various diagnostic modalities which could be used preoperatively as well as postoperatively to evaluate such cases. The importance of such a study is in the fact that early identification of these nonmature cases give us an opportunity to act timely to salvage the failing AVF.
| Material and Methods|| |
The study is a hospital-based prospective observational study conducted by Department of Nephrology at our center, a tertiary care hospital in New Delhi. Patients were admitted consecutively starting July 2018 for their first preemptive RC-AVF surgery until the sample size was met. The trial protocol was cleared by the Institutional Ethics Committee. The inclusion criteria were a normal Allen test on the clinical examination (CE) with unharmed forearm having patent compressible veins with at least 6 cm linear course. Patients with thrombosed venous system, preexisting skin lesions at surgical site, or surgical scars were excluded from the study.
These patients were then explained the surgery in detail and a written informed consent was taken. The nondominant hand was chosen for surgery, his demographic details and biochemical parameters were noted. A preoperative clinical and DUS (Doppler-Ultrasonography) examination was done on the feeding artery and draining veins of the forearm for their distensibility, calcification, and resistivity. The findings were noted in the proforma. Later, the patient was operated upon for RC-AVF by the same surgeon as an elective procedure in the routine operation room. Intraoperatively, any accessory veins within 6 cm of the anastomosis were ligated and the superficial fascia of the veins was cleared to allow for arterialization. Postoperatively, patients were discharged the same day and regular isometric hand grip exercise was advised. They were asked to follow-up on 4 weeks and 6 weeks postsurgery for suture removal and re-examination. Maturation of AVF was defined by usability of the AVF for the purpose of hemodialysis with adequate blood flow by 6 weeks. If an AVF was nonmature by 4 weeks, another 2 weeks were given for maturation. End point was defined by ability to use AVF for dialysis or nonmaturity at 6 weeks [Figure 1].
|Figure 1: Flow chart showing the allocation of subjects in the study group|
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Sample size was calculated using the following formula:
n = z2*p*q/L2, where P is prevalence, q = 1-p, z = 1.96 at 98% confidence interval, L is absolute error (10%)
Statistical analysis was done using the Statistical Package for the Social Sciences (SPSS) version 21.0 (IBM SPSS Statistics. Headquarter in Chicago, USA). Quantitative variables were compared using Independent t-test/Mann–Whitney test and qualitative variables were correlated using the Chi-square test/Fisher's exact test. P <0.05 was considered statistically significant.
| Results|| |
Ninet-one cases [Table 1] were taken up for the study with no immediate postoperative thrombosis, slippage of ligature, or requirement of re-exploration. 54.9% cases out of the total had successful AVF use within 6 weeks of surgery [Figure 2]. The study participants were then compared based on their demographic and preoperative DUS profile for various factors which could determine maturation. The mean age in the matured group was 46.04 ± 16.57 years with 36% females, while that in the nonmatured group was 58.17 ± 13.42 years with 58% females showing a significant association of age and sex. Forty-two percent of participants with a matured AVF were diabetics, whereas 65% of those with nonmatured AVF were diabetics showing statistical significance.
|Figure 2: Showing the time trend of Arterio-Venous fistula maturation. The success of Arterio-Venous fistula and the time at which they became matured for hemodialysis|
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Preoperative mean diameter of anastomotic vein on DUS in matured AVF cases was 0.20 ± 0.03 cm as compared to 0.19 ± 0.07 cm in failed cases (P = 0.01) [Figure 3]. Similarly, preoperative mean diameter of feeding artery in matured cases was 0.21 ± 0.04 cm, whereas 0.19 ± 0.03 cm in nonmatured (P = 0.0001). The ROC applied to these findings gave a diameter of 0.18 cm as a cut off to exclude cases [Figure 4].
|Figure 3: Showing the average diameter of vein in matured and nonmatured cases. The receiver operator curve shows that criteria of 0.18cm diameter of draining vein preoperatively can decide success of Arterio-Venous fistula with a sensitivity of 92%|
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|Figure 4: Showing the average diameter of artery in matured and nonmatured cases. The receiver operator curve shows that criteria of 0.18cm diameter of anastomotic artery preoperatively can decide success of Arterio-Venous fistula with a sensitivity of 98%|
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Calcification of anastomotic artery was seen in only 39.13% of matured cases as compared to 60.86% of nonmatured cases (P = 0.002). Resistive index (RI) was <0.7 in 80% of matured cases and ≥0.7 in 81% of failed cases. Moreover, RI had a sensitivity of 86% and a specificity of 73.17% for predicting AVF maturation outcomes [Table 2]. Preoperative incremental tests (IT) of the vein showed a positive result in 62% of matured cases and negative result in 76% of AVF failure cases (P = 0.006). It had a sensitivity of 92% and a specificity of 31.71% to diagnose matured cases.
|Table 2: The sensitivity and specificity of resistive index and incremental test to decide maturation of arterio-venous fistula|
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CE of the AVF at 4 and 6 weeks postsurgery found a sensitivity of 88.0% and specificity of 95.12% in confirming maturity of AVF. DUS was also done in all cases simultaneously to check for maturation of draining vein, blood flow, and its ability to sustain blood flow during hemodialysis with a positive predictive value of 94.34% and negative predictive value of 100% [Table 3].
|Table 3: Sensitivity and specificity of clinical examination and doppler-ultrasonography to assess maturation of arteriovenous fistula|
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| Discussion|| |
The primary failure rate of RC-AVF as calculated in our study was 45.1% at 6 weeks postsurgery without any surgical or radiological intervention. Causes for nonmaturation of AVF have been described by Asif et al., ranging from genetic predisposition, low shear stress, turbulence, differences in compliance between arteries and veins, and injury of the vessel during surgery.
Studies conducted by Manne et al. and Bahadi et al. showed a primary failure rate of 15.2% and 23.9%, respectively, for RC-AVF up to 3 months postsurgery. Similarly, studies conducted by Ascher et al. and Wolowczyk et al. had a primary failure rate of 18 and 20%, respectively. The discrepancy in the maturation rate of different studies can be explained by the differences in the inclusion criteria of these patients and the definition of success of AVF in different studies. KDOQI work group although now defines failure to mature of AV access as that which despite radiologic or surgical intervention cannot be used successfully for dialysis by 6 months after its creation.
Moving on, it has been very evidently shown in our study that age played a crucial role for deciding the success of AVF. The mean age of patients in the matured group was 46.04 ± 16.57 years, while that in other was 58.17 ± 13.42 years with a significant difference (P = 0.0002). A valid explanation for the same is that elderly population are more commonly diabetes, have calcified arteries and fibrosed, thickened, nondistensible veins making success of AVF difficult. A meta-analysis of 13 cohort studies showed that individuals with RC-AVF and above 50 years of age had a higher primary failure rate as compared to others. Similarly, Malovrh also showed in his study that a mean age of 50.5 ± 16.1 years as compared to 54.2 ± 17.6 years was associated with AVF maturation. Gender variation studied by Miller et al. showed that RC-AVF maturation was worse in women than in men (68% vs. 50%). Malovrh and Astor et al. in their study also found female gender to be associated with poor AVF outcome, whereas Wilmink et al. showed that female sex is an independent risk factor for RC-AVF nonmaturation with a lower functional rate of 65% vs. 86% in males (P < 0.0001 and odds ratio of 0.31). These discrepancies in maturation can be explained by the similar finding in our study as well as where females have a lower average artery and vein diameter, lesser distensibility of veins, and presence of deep veins in the forearm.
Diabetes has long been a culprit in AVF nonmaturation causing immense morbidity in these patients, inflammation of peripheral vessel leading to AVF stenosis and thrombosis. Apart from this, diabetes in itself causes hypertension, peripheral vascular disease, cardiovascular problems, vessel calcification, and nondistensibility which have independently proven to be harmful. In our study, 65% of those with nonmature AVF were diabetics. Similar studies conducted by Pogula et al. on RC-AVF showed that diabetics had more fistula failures and postoperative complications requiring multiple redo surgeries. Another retrospective analysis performed by Conte et al. and Smith et al. proved diabetes to be a negative predictor of AVF vein remodeling causing AVF nonmaturation.
Preoperative vein diameter
Preoperative evaluation of the veins of the hand without tourniquet showed that a mean diameter of 0.2 ± 0.03 cm was associated with successful maturation of AVF. It was further seen that 92% of matured AVF had a diameter of at least 0.2 cm. Recommendations on the minimum diameter for the veins of the arm are lacking, but many studies have come up with similar outcomes as ours. Wong et al. showed that AVF with a venous caliber of < 0.16 cm almost always fail, whereas Manne et al. showed similar finding with a vein diameter of <0.18 cm. Mendes et al. and Pogula et al., on the other hand, similar to our study proposed a diameter of 0.2 cm for successful maturation of RC-AVF.
Preoperative arterial diameter
Preoperative evaluation of the anastomosing artery of the hand showed that a mean diameter of 0.21 ± 0.04 cm was associated with successful maturation. Further it was seen that 98% of matured AVF had a diameter of at least 0.2 cm. Recommendations on the minimum diameter for the artery are lacking, but many studies have come up with similar results. A study conducted by Pogula et al. showed that a radial artery diameter of <0.25 cm had higher AVF failure rates as compared to others. Parmar et al. and Malovrh reported artery diameter <0.15 cm as a guiding parameter to decide maturation. Finally, Silva et al. in coherence with our study proposed a minimal diameter of 0.2 cm, which was associated with a low failure rate and a 1-year primary patency rate of 83%.
We found that almost 81% of AVF failure cases that had an abnormal RI index preoperatively. In fact we have shown that RI of the artery had a sensitivity of 86% and specificity of 73.17% to decide the success of RC-AVF. Further, it can also decide the negative predictive value of AVF with a very high frequency of 81.08%. Malovrh also showed similar findings in his study where RI < 0.7 had an AVF success rate of 87%, and negative predictive values are 74%. Wall et al., on the other hand, found no difference in primary patency of RC-AVF access based on hyperemic response of the artery. Hence, a clear conclusion is still doubtful.
In this study, it was observed that 62% of matured AVF had normal increment in draining veins preoperatively after 2 min of tourniquet application. Incremental capacity of the veins could decide the success of RC-AVF with a sensitivity of 92% and a specificity of 31.71% with a positive predictive value of 62.16%. Malovrh showed that patients with successful AVF maturation had 48% increment after tourniquet application preoperatively as compared to only 11.8% in the unsuccessful group (P < 0.01). Lockhart et al. and Silva et al. reported that dialysis adequacy of RC-AVF was better if they had incremental diameter of at least ≥ 2.5 cm after tourniquet application with 83% functional primary patency at 1 year.
Calcification of artery
It was shown in our study that 60.86% of cases who had AVF failure consisted of calcified arteries. The main reason for such an association has been explained by the fact that endothelium of a calcified vessel will not have the ability to modify itself and dilate in response to the increased demand. This finding has been confirmed previously as well by study done by Malovrh, who showed that patients with nonmatured RC-AVF had higher medial calcification of the artery (87% vs. 70%) as compared to the matured cohort. Choi et al. and Little et al. also showed positive association between arterial micro calcification and primary patency rate of RC-AVF.
The various aspects included in the examination are skin surface, vein firmness, vein engorgement, limb elevation test, pulse augmentation test, and presence of bruit with standard definitions.,, It is the most feasible and cost-effective approach for evaluation of AVF maturation and identification of delayed maturation of RC-AVF. In our study, CE of AVF was done at 4 weeks and 6 weeks postoperatively to check for dialyzability. We found that usability of AVF for dialysis was confirmed by CE with a sensitivity of 88.0% and a specificity of 95.12%. Furthermore, it could decide maturation of RC-AVF with a positive predictive value of 95.65% and successfully eliminate the failed cases. Other studies like the one by Beathard have talked about a proper algorithm by manual compression and pulse augmentation test to evaluate inflow lesions, inspection, and palpation of RC-AVF for accessory veins at 4–6 weeks. In another study conducted by Fereshteh et al., CE had an accuracy of over 70% and sensitivity of 100% to check for maturity. Asif et al. in another study successfully diagnosed almost all cases of nonmaturation of AVF by 8 weeks using CE.
All AVF were checked for their ability to sustain hemodialysis through USG-Doppler. It was found to have a sensitivity of 100% and a specificity of 92.68% using the KDOQI Guidelines., Asif et al. conducted a study on DUS and a found sensitivity of 89% and specificity of 99% to diagnose AVF nonmaturity. DUS is also a very accurate method for identifying stenotic arterial lesions with a sensitivity and specificity: 89 and 99% for those of the forearm, obstructive arterial lesions (sensitivity and specificity 90 and 99%) and thereby helping to diagnose failed AVF.
After a thorough assessment of AVF, the nonmatured AVF at the end of 6 weeks were tabulated according to the cause of failure [Table 4]. This result was then compared with other studies as well., In accordance with these studies,, we found that thrombosis of AVF and juxta anastomotic stenosis were the most common causes of AVF failure in our study.
|Table 4: The causes of nonmaturation of arteriovenous fistula in our study as confirmed by clinical and doppler-ultrasonography examination|
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| Conclusion|| |
In this study, we found out the various factors which could be checked preoperatively in a patient to predict the success of AVF surgery. We advise that an artery and vein diameter of < 0.2 cm is associated with poor AVF maturation. Further calcification of feeding artery, RI > 0.7 and poor increment of the draining vein are the independent factors which have a prominent role in deciding maturation of AVF. We also proved the relevance of CE and DUS in diagnosing these nonmatured cases earlier than they usually present with a very high-sensitivity rate.
Limitations of the study
We could not include certain variables such as obesity, social habits of smoking and alcohol, and presence of peripheral vascular disease in our population due to the large sample size and many variables. These were assumed to be distributed evenly in both the groups.
The authors would like to thank Department of Nephrology, Pushpawati Singhania Research Institute, New Delhi, India.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4]