Published online before print March 30, 2007, 10.1148/radiol.2432051232
(Radiology 2007;243:578-587.)
© RSNA, 2007
Vascular and Interventional Radiology |
Primary Patency with Cutting and Conventional Balloon Angioplasty for Different Types of Hemodialysis Access Stenosis1
Shuji Kariya, MD,
Noboru Tanigawa, MD,
Hiroyuki Kojima, MD,
Atsushi Komemushi, MD,
Yuzo Shomura, MD,
Tomokuni Shiraishi, MD,
Toshiaki Kawanaka, MD, and
Satoshi Sawada, MD
1 From the Department of Radiology, Kansai Medical University, 10-15 Fumizono, Moriguchi, Osaka 570-8507, Japan (S.K., N.T., H.K., A.K., Y.S., S.S.); and Departments of Radiology (T.S.) and Urology (T.K.), Ishikiri Seiki Hospital, Osaka, Japan. From the 2004 RSNA Annual Meeting. Received July 22, 2005; revision requested September 27; revision received December 21; accepted January 6, 2006; final version accepted September 5.
Address correspondence to S.K. (e-mail: shuuji{at}ops.dti.ne.jp).
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ABSTRACT
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Purpose: To compare primary patency rates of cutting balloon percutaneous transluminal angioplasty (PTA) (hereafter, cutting PTA) and conventional balloon PTA (hereafter, conventional PTA) in the treatment of different types of hemodialysis access stenosis.
Materials and Methods: The institutional review board approved this study. Written informed consent was obtained for the prospective component of this study and waived for the retrospective component. Patients in whom treatment with cutting PTA alone or conventional PTA alone was clinically successful formed the two study groups. Primary patency for the lesion was defined as uninterrupted patency of the treated site after balloon PTA. A site was no longer considered patent when the patient underwent treatment for hemodialysis access failure due to restenosis of the treated site. Primary patency rates for lesions were calculated with the Kaplan-Meier method according to the type of stenosis. We compared the two groups by using the log-rank test to determine statistical significance.
Results: In the cutting PTA group, 62 patients with 77 stenoses (32 men, 30 women; mean age, 65.5 years ± 10.1 [standard deviation]) achieved clinical success. In the conventional PTA group, 52 patients with 68 stenoses (23 men, 29 women; mean age, 61.9 years ± 10.2) achieved clinical success. In patients with autogenous venous stenosis, no significant difference in the primary patency rate was noted between groups (P = .369). In patients with graft-to-vein anastomotic stenosis, the primary patency rate was significantly higher for cutting PTA than for conventional PTA (P = .39). In patients with intragraft stenosis, no significant difference in the primary patency rate was noted between groups (P = .379). In patients with in-stent restenosis, no significant difference in the primary patency rate was noted between groups (P = .923).
Conclusion: Primary patency rates are significantly higher for cutting PTA in the treatment of graft-to-vein anastomotic stenosis; however, no significant differences in primary patency rates exist between these PTAs in the treatment of autogenous venous stenosis, intragraft stenosis, or in-stent restenosis.
© RSNA, 2007
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INTRODUCTION
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The Dialysis Outcomes Quality Initiative guidelines of the National Kidney Foundation recommend that balloon percutaneous transluminal angioplasty (PTA) be performed to treat hemodialysis access stenosis. With use of PTA, it is not difficult to achieve the reasonable patency goals described in these guidelines (1–5). Furthermore, secondary patency can typically be maintained with repeated PTA (2). However, since patients undergoing long-term dialysis require hemodialysis access for long periods of time, improvement in primary patency rates would reduce the number of PTAs performed. Thus, the purpose of our study was to compare primary patency rates of cutting balloon PTA (hereafter, cutting PTA) and conventional balloon PTA (hereafter, conventional PTA) in the treatment of different types of hemodialysis access stenosis.
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MATERIALS AND METHODS
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All study protocols (both prospective and retrospective) were approved by our institutional review board. Written informed consent was obtained for the prospective component of this study and was waived for the retrospective component.
Study Design
Cutting PTA was performed in all patients with stenosis in whom cutting PTA was indicated (see below) from January through September 2003, and primary patency rates were investigated prospectively. The primary patency rates of these stenoses were compared with rates determined retrospectively for stenoses treated with conventional PTA at our institution between October 2000 and August 2002.
During the study period, the first author (S.K.), a radiologist with 12 years of experience in interventional therapy, evaluated all indications for PTA; performed PTA, including conventional PTA and cutting PTA; measured vessel diameters; and monitored each patient's clinical course. All demographic and procedural data were obtained from a quality assurance database maintained by the first author. These data included access type and location, technical details of the procedure, complications, and procedure outcome. At our institution, atherectomy is not performed during PTA for hemodialysis access stenosis; thus, balloon PTA was performed in all patients. In some patients with thrombotic occlusion, balloon PTA was performed after percutaneous thrombolysis or thrombectomy (see below). The following complications were recorded and evaluated: balloon rupture, vascular injury, hemorrhage, hypotension, allergic reaction, infection, pulmonary embolism, ischemia of the hand, hypoxia, and death. All complications that occurred during postoperative follow-up were recorded and evaluated.
Patients
In all patients, an autogenous fistula or polyurethane graft (5 or 6 mm in diameter) was placed in either the forearm or the upper arm. None of the patients, except those with in-stent restenosis, underwent previous PTA. In patients with in-stent restenosis, self-expandable metallic Easy Wallstents (Boston Scientific, Natick, Mass) had been placed. Patients with in-stent restenosis presented with symptoms of stenosis for the first time after stent placement.
Criteria for PTA
According to Dialysis Outcomes Quality Initiative guidelines, all PTAs were performed in patients who exhibited more than 50% stenosis and clinical abnormalities (1). Clinical abnormalities included abnormal physical examination findings (changes in bruits, thrills, pulse, etc); abnormal urea recirculation measurements, as defined in the Dialysis Outcomes Quality Initiative protocol; elevated venous pressure during dialysis; decreased access flow; previous thrombosis in the access line; development of collateral veins; limb swelling; low arterial pressure during dialysis; and/or unexplained decreases in dialysis dose (1).
Criteria for Cutting PTA
For hemodialysis access, the diameter of a normal vessel adjacent to a fistula and the diameter of the adjacent graft were both 5–8 mm, as this was the inflation diameter of cutting balloons available from January through September 2003. Bending curvature of stenosis was set at less than 45° to avoid rupturing the cutting balloon.
Cutting PTA Group
Subjects who underwent cutting PTA comprised 72 patients with 87 stenoses (32 men, 40 women) that matched the indication criteria for PTA from January through September 2003. Mean age was 64.7 years ± 9.9 (standard deviation). In the present study, primary subjects were those with stenoses in whom clinical success was achieved by using cutting PTA alone (cutting PTA group) and who also satisfied the criteria for cutting PTA. In this group, five of the 72 patients with thrombotic occlusion underwent thrombectomy with manual aspiration of clots through an introducer sheath and thrombolysis with local infusion of urokinase (60 000 IU), mechanical thrombolysis with a percutaneous thrombolytic device (PTD; Arrow International, Reading, Pa), or both.
Conventional PTA Group
Conventional PTA was performed in 67 patients with 98 stenoses (32 men, 35 women) that matched the indication criteria for PTA from October 2000 through August 2002. Mean age was 61.8 years ± 10.6. Of these 67 patients, those with findings that matched the indication criteria for cutting PTA were excluded. In our study, primary subjects were those in whom clinical success was achieved by using conventional PTA alone (conventional PTA group). In this group, thrombectomy with manual aspiration of clots through the introducer sheath and thrombolysis with local infusion of urokinase (60 000 IU) was performed in three of the 67 patients with thrombotic occlusion.
Stenosis Assessment
Fistulography was performed just before balloon PTA to measure vessel diameter. In fistulography, an anterograde contrast medium (Iopamiron; Nihon Schering, Osaka, Japan) was injected through either a 5–7-F introducer sheath (Supersheath; Medikit, Miyazaki, Japan) that was placed as an access device for balloon angioplasty or a 21-gauge elastor needle placed in the brachial artery. To measure vessel diameter, a 0.035-inch measuring guidewire (Interslue; Clinical Supply, Gifu, Japan) was inserted into the hemodialysis access site from the introducer sheath. The guidewire was used for calibration purposes.
Digital subtraction angiography (Ultimax; Toshiba Medical Systems, Tochigi, Japan) was performed, and vessel diameter was measured at a workstation (Digital Image System; Toshiba Medical Systems) connected to the angiography machine (S.K.).
Procedures and Clinical Success
All procedures were performed on an outpatient basis with conscious sedation and analgesia induced by using midazolam (Dormicum; Yamanouchi Pharmaceutical, Tokyo, Japan) and pentazocine (Pentagin; Sankyo, Tokyo, Japan) titrated to effect. Anticoagulants (intravenous heparin, 2000 IU) were administered at the discretion of the attending interventional radiologist for prophylactic angioplasty procedures. Initial balloon size was determined with the same technique used to determine the expected vessel diameter in a fistula or the diameter of the adjacent graft. A 5–7-F introducer sheath was used as an access device for balloon angioplasty in all patients. In patients with an autogenous fistula, the introducer sheath was placed in the draining vein. In patients with a graft, the introducer sheath was placed in the graft or drainage vein. In all patients, an area without marked curvature in the route to the site of stenosis was selected. In cutting PTA, a 1-cm-long cutting balloon (Peripheral Cutting Balloon; Boston Scientific) rated as having a burst pressure of 10 atm and with an inflation diameter of 5–8 mm was used. In conventional PTA, 2–4-cm long conventional balloons (Ultrathin Diamond, Synergy, or Sasuga; Boston Scientific) rated as having a burst pressure of 15, 12, and 16–18 atm, respectively, and with an inflation diameter of 5–8 mm were used. A pressure inflation device (Everest; Medtronic, Minneapolis, Minn) was used for balloon inflation in all procedures.
Clinical success of conventional or cutting balloon PTA was defined as an improvement in hemodialysis access failure and resumption of normal dialysis for at least one dialysis session after PTA. Clinical success was determined by a urologist (T.K.) with 20 years of experience performing dialysis.
Technique for Cutting PTA
The lesion was crossed by using a 0.018-inch guidewire (Transend; Boston Scientific), over which the cutting balloon was introduced. First, the cutting balloon was inflated for 60 seconds at 4 atm for two attempts. On the third inflation, if the balloon waist remained at the same pressure as on the second inflation, pressure was subsequently increased by 2 atm. In this manner, each balloon was inflated repeatedly until the balloon waist disappeared. Once the balloon was completely inflated for 60 seconds on any attempt, the inflation procedure was stopped. Since the rated burst pressure for the cutting balloon recommended by the manufacturer was 10 atm, maximum pressure was set at 10 atm. Even if the balloon waist remained after a third inflation at 10 atm, the inflation procedure was terminated. After an inflation ended, the deflated cutting balloon catheter was rolled before the next inflation. The reason for rolling the cutting balloon catheter was so the blade attached to the balloon would cut the vessel wall at a different site each time.
Technique for Conventional PTA
The lesion was crossed by using a 0.035-inch guidewire (Interslue), over which the balloon was introduced. Each balloon was inflated to a level below the rated burst pressure recommended by the manufacturer until the balloon waist disappeared; then it was inflated for 60 seconds. If the balloon waist still remained when the rated burst pressure was reached, the balloon was inflated for 60 seconds for no more than three attempts until the balloon waist disappeared below the rated burst pressure. Even if the balloon waist remained after the third inflation attempt, the inflation procedure was terminated without a fourth attempt.
Follow-up
In both groups, clinical findings (change in bruits, thrills, pulse, etc) were noted at physical examination, venous dialysis pressure was recorded during each hemodialysis session, and monthly measurements of dialysis dose and urea recirculation were obtained. Access flow measurements were obtained with ultrasonography (US) every 2–3 months by a clinical technologist with 15 years of experience in US. Fistulography was performed (S.K.) when abnormal results were obtained. Follow-up findings were classified during the quality assurance process (S.K.) by means of communication at our access meetings with sonographers and staff in the dialysis units.
Statistical Analysis
Balloon diameter, percent diameter stenosis before PTA, residual percent diameter stenosis after PTA, and percent diameter dilatation (ie, residual percent diameter stenosis after PTA minus percent diameter stenosis before PTA) in the cutting PTA group and the conventional PTA group were compared by using the Mann-Whitney U test. Hemodialysis access stenosis was divided into the following four types: (a) autogenous venous stenosis (stenosis of venous runoff from arterial-venous anastomosis to central veins), (b) graft-to-vein anastomotic stenosis, (c) intragraft stenosis, and (d) in-stent restenosis. For these four types, the patency curves were then created with the Kaplan-Meier method and compared with the results of log-rank statistics in the cutting and conventional PTA groups.
Primary patency for the lesion was defined as uninterrupted patency of the treated site after balloon PTA. The end point of patency was decided at the time of treatment for hemodialysis access failure due to restenosis of the treated site. However, when a lesion other than that at the treated site caused hemodialysis access failure, primary patency for the lesion was not interrupted. As patients in the cutting and conventional PTA groups underwent the procedure at different times, observation periods also differed. Maximum duration of patient follow-up was set at 450 days, and data obtained in all stenoses that maintained patency on day 450 of follow-up were considered censored and subjected to log-rank testing. Data were analyzed in January 2005, and in the cutting PTA group, the interval between the last procedure and data analysis was more than 450 days. As the sample size was small, the 
2 test or Fisher exact test for 2 x 2 tables (Table 1) was used to compare patency rates (number of patients with patent stents divided by the total number of patients) for various time points (2nd, 3rd, 4th, 5th, 6th, 9th, 12th, and 15th months) between cutting and conventional PTA groups for the four types of stenosis. P values of less than .05 were considered to indicate a statistically significant difference. All analyses were performed by using StatView, version 5.0, software (SAS Institute, Cary, NC).
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RESULTS
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Cutting PTA
Of the 72 patients with 87 stenoses that matched the indication criteria for PTA from January through September 2003, 69 patients with 84 stenoses satisfied the indication criteria for cutting PTA. Of the three patients who did not satisfy the indication criteria for cutting PTA, one had autogenous arterial venous anastomotic stenosis that required a balloon with an inflation diameter of less than 5 mm and a bending curvature of at least 45°, and two had a central vein stenosis that required a balloon with an inflation diameter of more than 8 mm. Of the 69 patients with 84 stenoses who satisfied the indication criteria, 62 patients with 77 stenoses (32 men, 30 women; mean age, 65.5 years ± 10.1) achieved clinical success with cutting PTA alone. The clinical success rate was 90% with cutting PTA alone. Clinical success could not be achieved with cutting PTA alone in seven patients with seven stenoses; these patients required additional stent implantation (n = 6) or surgical reconstruction (n = 1). Of the 77 stenoses, 54 were autogenous venous stenoses, seven were graft-to-vein anastomotic stenoses, six were intragraft stenoses, and 10 were in-stent restenoses. None of the 77 stenoses was present in the central vein, inflow artery, or autogenous arterial venous anastomosis. Three patients with thrombotic occlusion were included among the 62 patients in whom clinical success was achieved.
Regarding the inflation diameter of the cutting balloons used, the mean loaded maximum pressure was 5.9 atm ± 2.0 for autogenous venous stenosis, 6.3 atm ± 2.7 for graft-to-vein anastomotic stenosis, 8.0 atm ± 2.2 for intragraft stenosis, and 8.2 atm ± 2.4 for in-stent restenosis (Table 2). In the cutting PTA group, the mean percent diameter stenosis before PTA, mean residual percent diameter stenosis after PTA, and mean percent diameter dilatation after PTA, respectively, were 81.3% ± 12.0, 31.2% ± 15.5, and 50.1% ± 18.5 for autogenous venous stenosis; 81.7% ± 16.2, 35.7% ± 12.7, and 46.0% ± 11.0 for graft-to-vein anastomotic stenosis; 67.6% ± 18.9, 41.1% ± 16.0, and 26.6% ± 13.3 for intragraft stenosis; and 74.6% ± 5.5, 35.0% ± 11.2, and 39.7% ± 11.0 for in-stent restenosis (Table 3).
Conventional PTA
Of the 67 patients who had 98 stenoses that matched the indication criteria for PTA and underwent conventional PTA between October 2000 and August 2002, 58 patients with 76 stenoses also satisfied the indication criteria for cutting PTA. The nine patients who did not meet the indication criteria for cutting PTA had autogenous arterial venous anastomotic stenosis that required a balloon with an inflation diameter of less than 5 mm, a bending curvature of at least 45°, or both (n = 3); central vein stenosis that required a balloon with an inflation diameter of more than 8 mm (n = 2); arterial stenosis that required a balloon with an inflation diameter of less than 5 mm (n = 1); or autogenous vein stenosis that required a balloon with an inflation diameter other than 5–8 mm (n = 3). Of the 58 patients who satisfied the indication criteria for cutting PTA, 52 patients with 68 stenoses (23 men, 29 women; mean age, 61.9 years ± 10.2) achieved clinical success with conventional PTA alone. Clinical success rate was 90% with conventional PTA alone. Clinical success could not be achieved with conventional PTA alone in six patients who required additional stent implantation (n = 5) or surgical reconstruction (n = 1). Stenosis type for the 68 stenoses was autogenous venous stenosis (n = 38), graft-to-vein anastomotic stenosis (n = 14), intragraft stenosis (n = 9), or in-stent restenosis (n = 7). None of these 68 stenoses occurred in the central vein, inflow artery, or autogenous arterial venous anastomosis. Two patients with thrombotic occlusion were included among the 52 patients in whom clinical success was achieved.
The mean loaded maximum pressure (Table 2) was 14.6 atm ± 3.2 for autogenous venous stenosis, 16.0 atm ± 4.2 for graft-to-vein anastomotic stenosis, 17.0 atm ± 2.4 for intragraft stenosis, and 14.7 atm ± 3.0 for in-stent restenosis. The mean percent diameter stenosis before PTA, mean residual percent diameter stenosis after PTA, and mean percent diameter dilatation after PTA, respectively, were 73.6% ± 14.3, 27.2% ± 13.0, and 46.4% ± 17.7 for autogenous venous stenosis; 68.1% ± 13.4, 31.3% ± 12.3, and 37.0% ± 14.3 for graft-to-vein anastomotic stenosis; 63.1% ± 9.5, 27.6% ± 8.7, and 35.5% ± 14.1 for intragraft stenosis; and 71.7% ± 6.1, 22.9% ± 15.0, and 48.8% ± 13.7 for in-stent restenosis (Table 3).
Cutting PTA and Conventional PTA Groups
No significant differences in balloon diameter between cutting PTA and conventional PTA groups were seen for any type of stenosis (Table 2). No significant differences in percent diameter stenosis were seen between cutting PTA and conventional PTA groups before PTA for graft-to-vein anastomotic stenosis (P = .062), intragraft stenosis (P = .860), or in-stent restenosis (P = .329). A significant difference in percent diameter stenosis was seen between the groups for autogenous venous stenosis (P = .010) (Table 3). No significant differences between cutting PTA and conventional PTA groups were seen in residual percent diameter stenosis after PTA for autogenous venous stenosis (P = .327), graft-to-vein anastomotic stenosis (P = .371), or in-stent restenosis (P = .097). A significant difference in residual percent diameter stenosis was seen between the groups for intragraft stenosis (P = .029). No significant differences between cutting PTA and conventional PTA groups were seen in percent diameter dilatation after PTA for autogenous venous stenosis (P = .312), graft-to-vein anastomotic stenosis (P = .101), intragraft stenosis (P = .289), or in-stent restenosis (P = .143).
Primary Patency Rates for Autogenous Venous Stenosis
For cutting PTA alone, the 6-month patency rate was 84.6% and the 1-year patency rate was 61.5% according to Kaplan-Meier analysis results. For conventional PTA alone, the 6-month patency rate was 55.0% and the 1-year patency rate was 48.5%, as calculated with the Kaplan-Meier method. No significant differences (P = .369) in primary patency rates were identified between groups by using Kaplan-Meier analysis (Fig 1). With use of the 2 or Fisher exact tests, patency rates in the cutting PTA group were found to be significantly higher than those in the conventional PTA group in the 5th, 6th, and 9th months (P = .016, P = .014, and P = .003, respectively) (Table 4).
Primary Patency Rates for Graft-to-Vein Anastomotic Stenosis
For cutting PTA alone, the 6-month patency rate was 71% and the 1-year patency rate was 57% according to Kaplan-Meier analysis results. For conventional PTA alone, the 6-month patency rate was 38% and the 1-year patency rate was 7% according to Kaplan-Meier analysis results. With use of Kaplan-Meier methods, the primary patency rate was significantly higher for cutting PTA than for conventional PTA (P = .039) (Fig 2). With use of the 2 or Fisher exact tests, the patency rate was significantly higher for cutting PTA than for conventional PTA in the 9th month (P = .031) (Table 5).
Primary Patency Rates for Intragraft Stenosis
For cutting PTA alone, the 6-month patency rate was 50% and the 1-year patency rate was 50% according to Kaplan-Meier analysis results. For conventional PTA alone, the 6-month patency rate was 75% and the 1-year patency rate was 12%, as calculated with the Kaplan-Meier method. With use of Kaplan-Meier analysis, no significant differences in primary patency rates were identified between the groups (P = .379) (Fig 3). With use of the 2 or Fisher exact tests, no significant differences in patency rates were identified between the groups at any follow-up point (Table 6).
Primary Patency for In-Stent Restenosis
For cutting PTA alone, the 6-month patency rate was 30% and the 1-year patency rate was 20% according to Kaplan-Meier analysis results. For conventional PTA alone, the 6-month patency rate was 57% and the 1-year patency rate was 14%, as calculated with the Kaplan-Meier method. No significant differences in primary patency rates were noted between the groups with use of the Kaplan-Meier method (P = .923) (Fig 4). With use of the 2 or Fisher exact tests, no significant differences in patency rates were identified between the groups at any time point (Table 7).
Complications in Cutting PTA
Balloon rupture occurred in one of 84 stenoses, but subsequent angiography revealed no extravasation. No postoperative extravasation or aneurysmal dilatation was seen in two stenoses, but angiography performed 3 months after cutting PTA revealed aneurysmal dilatation at the site of balloon inflation. Diameter of aneurysmal dilatation was less than 2 cm in both lesions. Follow-up testing conducted 1 year after PTA showed no aneurysmal diameter increase, and aneurysmal dilatation did not affect hemodialysis. Cutting PTA did not cause any other complications.
Complications in Conventional PTA
Balloon rupture occurred during inflation in two of the 76 stenoses, but angiography revealed no extravasation. Extravasation occurred immediately after balloon inflation in two patients, and hemostasis was achieved by inflating the same balloon with 2 atm of pressure in the same location to apply compression from inside the vessel and by manually applying external compression for 5 minutes. Extravasation disappeared and clinical success was achieved in only one patient. In the other patient, clinical success could not be achieved because blood flow was stopped due to hematoma, and hematoma surrounding the lesion was removed surgically. Conventional PTA did not cause any other complications.
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DISCUSSION
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Two advantages are associated with cutting PTA. The first is that favorable inflation can be achieved, even in patients with severe stenosis. Even when the rated burst pressure recommended by the manufacturer is applied, conventional PTA may not result in dilatation of severe stenoses because of the balloon waist; however, if cutting PTA is performed, the balloon can fully inflate and residual stenosis can be reduced (6,7). In addition, even when residual stenosis is caused by elastic recoil in conventional PTA, use of a cutting balloon alleviates residual stenosis in patients with coronary artery stenosis (8). The first advantage of cutting PTA also applies to hemodialysis access stenosis, and the findings of several studies have shown that initial results for combined conventional and cutting PTA are favorable (9–11). In our study, no significant differences in residual percent diameter stenosis were noted between cutting PTA and conventional PTA in the treatment of autogenous venous stenosis, graft-to-vein anastomotic stenosis, intragraft stenosis, or in-stent restenosis. However, residual percent diameter stenosis tended to be higher for cutting PTA than for conventional PTA in the treatment of intragraft or in-stent restenosis, although no significant difference was identified. Several studies have revealed that residual stenosis can be improved by performing cutting PTA in patients with severe residual stenosis after conventional PTA (9–11). Given our results, cutting PTA appears to be effective in reducing residual percent diameter stenosis in lesions that are unresponsive to conventional PTA.
The second advantage of cutting PTA is that because the balloon is inflated around the incision, it can be inflated at a lower pressure, with resultant reduced damage to the vascular wall (7,12). Conversely, the excessive dilation force applied to flexible regions during conventional PTA in patients with arterial stenosis can reportedly cause vascular damage. Tissue regeneration in the region of vascular damage then leads to the proliferation of smooth muscle cells and excessive growth of the newly generated inner membrane, which result in restenosis (13). A longer period of patency can thus be expected with cutting PTA because of the reduction in vascular wall damage (7).
In regard to hemodialysis access stenosis, Davidson et al (12) used intravascular US to assess changes after conventional PTA for hemodialysis access stenosis and reported that plaque dissection and vessel stretching were seen in 10 of 24 (42%) and 15 of 24 (63%) cases, respectively, and that angioplasty mechanisms were based on dissection and vessel stretching. This finding suggests that even in patients with hemodialysis access stenosis, conventional PTA may cause vascular damage, which could result in restenosis. According to these findings, vascular damage caused by high pressure inflation might lead to restenosis in patients with hemodialysis access stenosis. Thus, cutting PTA appears to be a technique with which longer periods of patency can be expected, even in patients with hemodialysis access stenosis. However, in most studies in which patency rates in cutting PTA and conventional PTA groups have been compared, researchers have investigated only coronary artery stenosis and—to our knowledge—no previous studies have been performed to examine hemodialysis access stenosis.
Cutting PTA performed to treat hemodialysis access stenosis is often combined with conventional PTA (9–11); however, to maximize the second advantage as mentioned previously (ie, because the balloon is inflated around the incision, it can be inflated at a lower pressure, with resultant reduced damage to the vascular wall), cutting PTA should be performed first. This is because dilation damages the vascular wall if conventional PTA is performed first. Singer-Jordan and Papura (14) performed cutting PTA first in patients with hemodialysis fistula venous stenosis and noted that the 6-month patency rate was 76%. However, those procedures included additional stent placement and additional PTA with a larger-diameter conventional balloon, so comparison with the results of other published series is difficult (15).
We found that in patients with autogenous venous stenosis and those with graft-to-vein anastomotic stenosis, the amount of vascular wall damage induced by cutting PTA was less than that induced by conventional PTA; therefore, the primary patency rate for cutting PTA was thought to be higher than that for conventional PTA. As our results of log-rank testing show, a longer period of primary patency achieved by performing cutting PTA alone might be expected only in patients with graft-to-vein anastomotic stenosis; however, the sample size was insufficient to determine if there was a significant difference. However, Kaplan-Meier curves and the results of 2 testing indicate a possibility that longer periods of primary patency achieved by performing cutting PTA alone could be expected for autogenous venous stenosis and graft-to-vein anastomotic stenosis at some point after PTA.
No significant differences existed between the cutting PTA and conventional PTA groups in terms of primary patency rates for intragraft stenosis or in-stent restenosis. The reasons for this may be two-fold. First, because of the presence of a circumferential artificial structure in the vascular wall, no structurally weak areas were present. Even when high pressure was applied for balloon inflation, minimal vascular damage resulted from dissection and vessel stretching, which can lead to restenosis. Second, among patients with in-stent restenosis or intragraft stenosis, residual percent diameter stenosis for conventional PTA tended to be smaller—albeit not significantly smaller—for in-stent restenosis.
In patients with coronary in-stent restenosis, Schiele et al (16) reported that the mechanisms of cutting PTA, as assessed with intravascular US, do not differ significantly from those of conventional PTA and predominantly comprise additional stent expansion and a decrease in neointimal mass achieved with a combination of compression and transverse redistribution. They concluded that the performance of cutting PTA for treatment of in-stent restenosis might not be superior to that of conventional PTA. Thus, we think that for hemodialysis access in patients with intragraft stenosis or in-stent restenosis, residual stenosis can be minimized by performing conventional PTA with a higher pressure to compress the neointimal mass rather than by performing cutting PTA.
In one study in which patency rates were compared between cutting PTA and conventional PTA groups, researchers found no significant differences in patients with in-stent restenosis of the coronary artery (17). In our study of hemodialysis access stenosis, we acheived comparable results for cutting PTA and conventional PTA in patients with in-stent restenosis of the hemodialysis access. When cutting PTA was performed to treat intragraft stenosis or in-stent restenosis, primary patency was not significantly improved, and residual percent diameter stenosis was greater for cutting PTA than for conventional PTA. As a result, no advantage was obtained by using a cutting balloon in the treatment of intragraft stenosis or in-stent restenosis.
In the cutting PTA group, aneurysmal dilatation at the site of inflation was seen during follow-up in two stenoses. However, aneurysmal dilatation did not increase in size and did not cause any dialysis failure. Aneurysmal dilatation could have been caused by an incision in the vascular wall created by a blade; thus, patients need to be monitored for a certain period of time after cutting PTA.
Our study was limited by the small number of subjects and by the fact that patients underwent cutting PTA and conventional PTA during different time periods. The cutting PTA group underwent the procedure between January and September 2003. This was the prospective portion of the investigation. However, the conventional PTA group underwent the procedure between October 2000 and August 2002. This was the retrospective part of our investigation, as our study was started in January 2003. Thus, our study was not a randomized controlled trial. Future randomized controlled studies are warranted.
In conclusion, primary patency rates are significantly higher for cutting PTA than for conventional PTA in the treatment of graft-to-vein anastomotic stenosis. However, no significant differences are apparent in primary patency rates between cutting PTA and conventional PTA groups in the treatment of autogenous venous stenosis, intragraft stenosis, or in-stent restenosis. These data suggest that cutting PTA should be performed to treat graft-to-vein anastomotic stenosis.
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ADVANCES IN KNOWLEDGE
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- Primary patency rates are significantly higher for cutting balloon percutaneous transluminal angioplasty (PTA) than for conventional balloon PTA in the treatment of graft-to-vein anastomotic stenosis.
- No significant differences in primary patency rates between cutting balloon PTA and conventional balloon PTA groups are apparent in the treatment of autogenous venous stenosis, intragraft stenosis, or in-stent restenosis.
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FOOTNOTES
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Abbreviations: PTA = percutaneous transluminal angioplasty
Authors stated no financial relationship to disclose.
Author contributions: Guarantor of integrity of entire study, S.K.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; manuscript final version approval, all authors; literature research, S.K., N.T., H.K., Y.S., S.S.; clinical studies, S.K., N.T., H.K., A.K., T.S., T.K.; statistical analysis, S.K., N.T., A.K., S.S.; and manuscript editing, S.K., N.T., H.K., A.K., Y.S., S.S.
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References
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ABSTRACT
INTRODUCTION
) (n = 54) and conventional PTA (
) (n = 38) groups. No significant differences in primary patency rates were identified between groups.
