Periodic Duplex Ultrasonography Screening Together with Elective. Percutaneous Transluminal Angioplasty in the Management of. Graft Arteriovenous Fistulas ...
Surg Today (2006) 36:775–778 DOI 10.1007/s00595-006-3252-3
Periodic Duplex Ultrasonography Screening Together with Elective Percutaneous Transluminal Angioplasty in the Management of Graft Arteriovenous Fistulas for Hemodialysis Naoki Toya, Tetsuji Fujita, Hiromichi Hagiwara, Makoto Sumi, Koji Kurosawa, Yuka Negishi, Hiromasa Tachihara, and Katsuhiko Yanaga Department of Surgery, Jikei University School of Medicine, 3-25-8 Nishishinbashi, Minato-ku, Tokyo 105-8461, Japan
Abstract Purpose. To evaluate the effectiveness of regular duplex ultrasonography in the management of graft arteriovenous fistulas for hemodialysis. Methods. Between March 1997 and December 2004, we prospectively studied consecutive patients who underwent polytetrafluoroethylene graft arteriovenous (AV) fistulae in the upper extremity with a subsequent regular duplex ultrasound examination for the identification of stenosis. The main ultrasound-guided indication for percutaneous transluminal angioplasty (PTA) was the identification of 50% or more venous stenosis. The assisted primary and secondary patency rates of vascular access were calculated in these 36 patients and were then compared with those in 19 patients who had undergone graft AV fistula before the start of regular ultrasonographic screening. Results. The mean follow-up lasted 25 months. PTA procedures were performed in 24 patients, of which 13 patients received multiple PTAs. The half survival time (secondary patency) of the graft was 49 ± 3.8 months in patients who had undergone ultrasound screening followed by elective PTA, which was significantly (P < 0.01) longer than the 22 ± 7.1 months observed in patients who had not undergone regular duplex ultrasound screening. Conclusion. The prospective monitoring of AV fistula with ultrasound is a simple and reliable technique for detecting graft AV outflow stenosis. Elective PTA is therefore considered to be an effective therapy for the maintenance of hemodialysis access.
Introduction In patients who are on hemodialysis for chronic renal failure, the creation and maintenance of vascular access for dialysis is critical. Generally, the access of first choice is the native radiocephalic arteriovenous (AV) fistula. The implantation of polytetrafluoroethylene (PTFE) grafts is the second choice, which is used when the constriction of a native AV fistula is not possible, particularly due to the lack of a patent subcutaneous vein. Despite being the lifeline for patients on dialysis, a high rate of failure of dialysis access has been reported. According to a previous report, cumulative patency rates of radiocephalic fistulas at 1 and 2 years were 69% and 66%, respectively,1 whereas PTFE grafts have either a shorter or similar longevity than native AV fistulas.2,3 Thrombosis is the most common cause of occlusion of AV fistulas, and stenosis is preceded by thrombosis or total occlusion. Percutaneous transluminal angioplasty (PTA) has been advocated to alleviate stenosis of dialysis access sites. However, it is usually difficult to restore a totally occluded graft AV fistula by PTA.4 Therefore, the early detection of failing venous access for hemodialysis is important. Recently, duplex ultrasonography has been proven to be an accurate and noninvasive method for the diagnosis of such access complications as in comparison to access angiography.5,6 The aim of this study was to evaluate the significance of periodic duplex ultrasonography and subsequent PTA in the management of graft AV fistulas for hemodialysis.
Key words Percutaneous transluminal angioplasty · Graft arteriovenous fistula · Duplex ultrasonography Methods
Reprint requests to: N. Toya Received: December 13, 2005 / Accepted: May 16, 2006
Thirty-six consecutive patients who had undergone PTFE graft AV fistula in the upper extremity between March 1997 and December 2004 received duplex
N. Toya et al.: Elective PTA in Graft AV Fistula
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ultrasound examination monthly for identification of stenosis and a decreased blood flow in venous access sites. Ultrasonographic examinations were performed directly by an experienced radiologist with the use of a linear array ultrasound probe. First, careful morphological and color Doppler examinations of the arteries were performed. Detailed examinations of the arteries were followed by an inspection of the graft blood flow. Special attention was given to venous anastomosis and the adjacent segment of the outflow vein. The main ultrasound-guided indication for PTA was the identification of 50% or more venous stenosis (Fig. 1). The primary and secondary patency rates of vascular access were calculated in these 36 screened patients with periodic duplex ultrasonography and were then compared with those in 19 patients who had undergone a graft AV fistula before the start of periodic ultrasonographic screening. The assisted primary patency rate was defined as the time between the construction of a vascular access and its first failure. Secondary
patency was defined as the time between the construction of a vascular access and its ultimate failure, including all interventions. In the historical control group of 19 patients, a secondary patency was considered to be the same as a primary patency.7 All values were expressed as the mean ± SD, and/or range. Baseline differences between groups were tested by the unpaired t test. Patency rates were calculated using the Kaplan–Meier method, and the log-rank test was used to compare differences between curves. Univariate Cox proportional hazards models were used to analyze the association of sex, age, the presence or absence of diabetes mellitus (DM), and the operation site with the patency rate. P values less than 0.05 were considered to indicate a significant difference.
Results The two groups were similar, as shown in Table 1. The mean follow-up lasted 25 months, ranging from 1 to 77 months. PTA procedures were performed in 24 patients, in whom 13 patients received multiple PTAs. The half survival time of the graft (secondary patency) was 49 ± 3.8 months in the patients who underwent ultrasound screening followed by elective PTA; this was significantly (P < 0.01) longer than the 22 ± 7.1 months observed in patients without periodic duplex ultrasound screening (Fig. 2). Neither the demographic factors, the presence of DM, nor the anastomotic site was associated with secondary graft survival (Table 2).
Discussion
Fig. 1. Ultrasonography showing venous stenosis. White arrow indicates more than 50% venous stenosis
A failure of vascular access results in the need to undergo emergent percutaneous or surgical intervention, which has poorer results than elective procedures. We introduced regular duplex ultrasonographic screening for the early detection of stenosis of native and graft AV fistulas in patients having vascular access for hemo-
Table 1. Patient characteristics
No. of patients Age in years (range) Sex Male Female Diabetes mellitus Operation site Lower arm Upper arm
Without US
With US and elective PTA
19 64.8 ± 12.9 (40–87)
36 63.6 ± 9.5 (45–89)
14 5 4 (21%)
20 16 9 (25%)
9 10
10 26
US, ultrasonography; PTA, percutaneous transluminal angiography
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N. Toya et al.: Elective PTA in Graft AV Fistula Table 2. Logistic regression table for secondary patency
Age Sex Diabetes mellitus Operation site
95%
P
Exp (coefficient)
Lower
Upper
0.84 0.84 0.90 0.09
0.918 0.920 0.931 0.459
0.396 0.404 0.309 0.186
2.131 2.098 2.807 1.132
Fig. 2. Cumulative graft patency in patients with or without ultrasonographic (US) screening. Closed squares, secondary patency rates of access in patients with US screeing; closed circles, primary patency rates of access in patients with US; and closed triangles, primary patency (secondary patency) rates of access in patients without US. The half survival time of graft access in patients with US and subsequent intervention was significantly longer than that in patients without US (49 ± 3.8 months vs. 22 ± 7.1 months, respectively; P < 0.01)
dialysis in 1997. In comparison to the survival time of vascular access resulting from patients before the introduction regular ultrasonographic examination, the secondary patency time was significantly prolonged in patients who received regular ultrasonographic screening together with subsequent elective PTA. Duplex ultrasonography is a simple, noninvasive, inexpensive, and accurate method for the evaluation of the vascular access function. However, no clear evidence of a prolongation of access patency after an ultrasound examination has been demonstrated until recently. Malik et al. conducted the first prospective randomized study to determine whether regular ultrasonographic screening can significantly prolong the patency of PTFE grafts. The results of their study, published in 2005, showed that regular ultrasonographic screening for access stenoses together with their earlier treatment leads to a significant prolongation of cumulative patency.8 Our results of the secondary patency rates in patients who were screened by monthly ultrasound examinations were comparable with the results in patients screened at 3-month intervals. The optimal inter-
val of ultrasound screening should thus be determined in the future. Percutaneous transluminal angioplasty (PTA) has become an increasingly common modality for the treatment of hemodialysis access site stenosis. Patients on chronic hemodialysis for more than several years are likely to have multiple PTAs or surgical revisions. In addition, in this study, repeat PTAs were required in 46% of all patients. Repeat PTA procedures are more likely to be needed for graft AV fistulas than for native AV fistulas, because discrete fibrosis tends to frequently occur in graft–venous anastomosis. Therefore, ultrasonographic examination-guided elective PTA is essential for the long-term survival of graft AV fistula. Schwab et al. described the optimal timing of PTA using dynamic venous pressure as the primary screening technique.9 The overall patency rates in the current study were better than those reported in their study. It is therefore assumed that duplex ultrasonography is a better method for determining the optimal timing for PTA, thus leading to the long-term patency of graft fistulas. Fitzgerald et al. reported no significant differences in the patency rates among the procedure sites of blood access.10 Our study also showed the operation sites (upper or lower arm) to not be related to the patency rates. In conclusion, prospective monitoring with ultrasound is a simple and reliable technique for detecting graft AV outflow stenosis, and elective PTA is therefore considered to be an effective therapy for the maintenance of hemodialysis access.
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N. Toya et al.: Elective PTA in Graft AV Fistula 8. Malik J, Slavikova M, Svobodova J, Tuka V. Regular ultrasonographic screening significantly prolongs patency of PTFE grafts. Kidney Int 2005;67:1554–8. 9. Schwab SJ, Oliver MJ, Suhocki P, McCann R. Hemodialysis arteriovenous access: detection of stenosis and response to treatment by vascular access blood flow. Kidney Int 2001;59:358– 62. 10. Fitzgerald JT, Schanzer A, Chin AI, McVicar JP, Perez RV, Troppmann C. Outcomes of upper arm arteriovenous fistulas for maintenance hemodialysis access. Arch Surg 2004;139:201–8.
