| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Technical Innovation |
1 All authors: Division of Vascular–Interventional Radiology, Department of Radiology, Box 3808, Duke University Medical Center, Durham, NC 27710.
Received June 28, 2002;
accepted after revision August 29, 2002.
Address correspondence to J. M. Ryan.
Introduction
 Top Introduction Materials and MethodsResultsDiscussionReferences |
|---|
We have encountered several patients whose dialysis access has been threatened by the presence of large pseudoaneurysms. The presence of a pseudoaneurysm predisposes the patient to turbulent flow in the graft, with resultant thrombosis. In addition, the presence of a large pseudoaneurysm often presents the dialysis technician or nurse with difficulty in accessing the graft and may be painful and unsightly for the patient. To date, this problem has largely been dealt with either by surgical correction or by abandonment of the access.
We present four patients with dialysis access pseudoaneurysms in whom we salvaged the graft by using a covered stent (Wallgraft; Boston Scientific/Meditech, Newton, MA) to successfully treat the pseudoaneurysm. Several case reports in the literature discuss the use of covered stents for this application. However, those reports either emphasized not puncturing the covered stent after placement or used a type of covered stent that was not available in the United States at the time of the report [3, 4].
|
TopIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Data for this article were accumulated retrospectively from the radiology database, from the hospital informatics system, from patients' medical records, and from communication with patients and referring physicians. Clinical outcomes after Wallgraft therapy were recorded. Informed consent was obtained from all patients before Wallgraft placement, and the unproven nature of the therapy was explained to each patient. Institutional review board approval was obtained for this study.
Technique
In each case, routine fistulography and central venography were performed
before placement of the covered stent. The site and direction of the dialysis
graft puncture were selected to allow covered stent placement during the same
treatment session as the fistulography without requiring a new puncture site.
Either a 9- or a 10-French angiographic sheath was placed. The diameter of the
graft was measured using a calibrated guidewire. Appropriate Wallgraft
diameter and length were chosen, allowing approximately 15% oversizing for a
good seal. The Wallgraft was carefully positioned and deployed. Antibiotics
were not used routinely during or after deployment. Heparin (2000 U) was
administered in each case to prevent intraprocedural thrombosis. After
deployment of the covered stent and insertion of a purse-string suture at the
puncture site, the angiographic sheath was removed. The suture was removed at
the next dialysis treatment session.
Subjects
A 74-year-old woman with an axilloaxillary polytetrafluoroethylene bridge
graft that had been working well for 14 months presented with a large and
painful aneurysm on her anterior chest wall that caused technical difficulties
for the dialysis access nurse. The surgeon who had created the graft was
reluctant to either revise or abandon what was essentially one of the
patient's terminal graft possibilities. Angiography was performed that showed
the symptomatic pseudoaneurysm and two smaller aneurysms
(Fig. 1A). A calibrated
guidewire was inserted, and from this the diameter of the graft was measured.
The graft diameter measured 6 mm, and to allow oversizing and to achieve a
good seal we chose an 8 x 50 mm Wallgraft. The Wallgraft was deployed
with one operator externally compressing the aneurysm. A 7 x 40 mm
angioplasty balloon was used to tightly seal the ends of the stent to the
graft. Repeated angiography showed excellent flow and complete exclusion of
the aneurysm (Fig. 1B). The
patient underwent dialysis the following day uneventfully. The dialysis staff
were instructed to avoid puncturing the portion of the graft containing the
covered stent for 3 weeks, after which time the entire graft could be used. We
marked the graft position on the patient's skin with an indelible marker. At
the 9-month follow-up, the graft continued to work well. The pseudoaneurysm
did not recur.
|
|
A 69-year-old man with a forearm loop polytetrafluoroethylene bridge graft presented with a large pseudoaneurysm of the arterial limb of the graft, which created difficulty for the dialysis staff in gaining adequate access, as well as being painful and unsightly to the patient. Angiography and central venography were performed and showed pseudoaneurysms of both the arterial and venous limbs of the graft. The pseudoaneurysm of the arterial limb was the most problematic; therefore, it was decided to treat this pseudoaneurysm first (Fig. 2A). An 8 x 50 mm Wallgraft was chosen and deployed, with some external compression of the pseudoaneurysm. A second 8 x 30 mm Wallgraft was required to fully exclude the pseudoaneurysm, and complete exclusion of the pseudoaneurysm was obtained (Fig. 2B). Dialysis was performed 2 days later. The patient's skin was marked with an indelible marker, and the dialysis staff were instructed to avoid puncturing that portion of the graft for 3 weeks. During follow-up, no difficulty occurred in gaining access through the interstices of the Wallgraft. At 6 and 11 months after Wallgraft placement, the patient re-presented to interventional radiology for fistulography because of elevated venous pressures recorded during dialysis. Angiography on both occasions showed a tight stricture at the venous anastomosis. The portion of the graft containing the Wallgraft was visualized using compression of the outflow tract and was widely patent; the pseudoaneurysm did not recur (Fig. 2 C). At 11 months, the unsightly dilated area over the previous pseudoaneurysm had markedly regressed (Fig. 2D). The venous anastomotic structure underwent successful angioplasty with a 7 x 4 mm balloon on both occasions.
|
|
|
|
A 64-year-old woman with an upper arm basilic vein transposition presented with a large proximal pseudoaneurysm, recurrent access problems, and decreased flow rates during dialysis. Angiography showed the pseudoaneurysm to be adjacent to the arterial anastomosis with a short proximal landing zone. An 8 x 50 mm Wallgraft was placed. Because of the large aneurysm size and the short proximal landing zone, the Wallgraft position shifted immediately after deployment. Two additional 8 x 40 mm Wallgrafts were required to effect a seal. On this occasion, because of the anatomy of the graft, we were unable to avoid using the portion of the graft containing the Wallgraft for 3 weeks (the basilic vein took a deep course into the arm a short distance beyond the site of the Wallgraft). Therefore, the patient underwent dialysis the following day, and the portion of the Wallgraft was punctured. Four months later the access continues to work well. The pseudoaneurysm has not recurred.
A 63-year-old man presented with a painful pseudoaneurysm of the polytetrafluoroethylene bridge dialysis graft in his forearm (Fig. 3A). A 7 x 30 mm Wallgraft was placed that successfully excluded the pseudoaneurysm. The patient continued uneventfully for 3 months, when a second pseudoaneurysm appeared at a different site (Fig. 3B). Comparison with the original study clearly showed that the new pseudoaneurysm did not occur at the site of the previous angiographic sheath placement. Angiography revealed that the original pseudoaneurysm remained excluded, and no intimal hyperplasia was seen in the Wallgraft. Two new 7 x 30 mm Wallgrafts were deployed, and repeated angiography showed excellent flow and complete exclusion of the pseudoaneurysm (Fig. 3C). The patient underwent dialysis successfully 1 day later, and no further problems have been encountered with the graft during 3 months of follow-up. Cannulation of the graft through the Wallgraft has been uneventful.
|
|
|
|
TopIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
In two patients, we allowed a waiting period of 3 weeks before puncturing the portion of the graft containing the Wallgraft, and in two patients puncture of the covered stent was performed at the next treatment session. During the follow-up period (range, 3–11 months), all grafts remained patent and no treated pseudoaneurysm recurred.
Two patients underwent follow-up angiography, one for a new pseudoaneurysm (after 4 months) and one for elevated venous pressures (at 6 and 11 months). Imaging showed excellent flow through the previously treated portion of the grafts, with no angiographic recurrence of the treated pseudoaneurysm or of stent narrowing. The patient with elevated venous pressures underwent successful angioplasty of a tight venous anastomotic stricture on both occasions.
|
TopIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Dialysis graft pseudoaneurysms are not uncommon; they result from repeated puncturing of the graft or fistula at the same site. The skin over the graft becomes scarred and avascular, and these two factors contribute to pseudoaneurysm occurrence. Pseudoaneurysms are often associated with graft thrombosis, pain, cosmetic problems, infection, and difficulty accessing the graft. Delorme et al. [5] analyzed 52 surgically excised polytetrafluoroethylene grafts used as secondary vascular access in chronic hemodialysis patients. In that study, pseudoaneurysm formation at the site of repeated venipuncture was the main cause of surgical removal of the graft more than 2 years after implantation. Those authors advocated a careful needle-puncture technique, systematic rotation of puncture sites, and the use of a rigorous aseptic technique in preserving the long-term structural integrity of the vascular access. There are two conventional surgical approaches to treating graft pseudoaneurysms. One involves removal of the diseased portion of the graft and replacement with a new segment in an end-to-end fashion. A second approach involves ligating the affected portion of graft and placing a bypass graft.
Covered stents have been advocated for the treatment of aneurysms of various origins [3, 4, 6]. In previous reports regarding the use of covered stents for pseudoaneurysm of dialysis access grafts, the dialysis technicians have not then used the portion of the graft containing the covered stent for further access, citing concerns about recurrence and infection [6]. One study reported the use of the Cragg Endo-Pro covered stent (Boston Scientific, Watertown, MA) and reported early successful exclusion of the pseudoaneurysm. However, the patients in that study experienced recurrence of the pseudoaneurysm after repeated puncturing of the covered stent [4].
Our experience differs in that we advocated using the graft containing the covered stent soon after placement, and we exclusively used the Wallgraft covered stent. We initially instigated a waiting period of 3 weeks before allowing puncture of the Wallgraft. Our thinking was influenced by our surgeon's approach of waiting 6 weeks before using a new polytetrafluoroethylene graft. Some incorporation of the graft into the tissues occurs during this time. We theorized that some analogous incorporation of the Wallgraft might occur in the area of the thrombosed pseudoaneurysm, which would confer positional stability and reduce the potential for pseudoaneurysm recurrence. We could not use this approach in the third patient we treated because of the anatomy of the graft; therefore, in this patient a cannula was inserted through the covered stent at the next treatment session. Our fourth patient was also treated this way. We found that early cannulation through the Wallgraft did not appear to undermine the technique in these two patients, although the follow-up of these patients is of limited duration.
An unexpected result in one patient was that his pseudoaneurysm significantly diminished in size over time (Figs. 2B and 2D). We believe that some elasticity must have remained in the overlying tissues, and some regression of the thrombus must have occurred in the excluded portion of the graft.
Both the Cragg Endo-Pro and the Wallgraft are covered with woven low-porosity polyethylene terephthalate, but the interstices of the nitinol Cragg Endo-Pro are much bigger than the interstices of the supermetal alloy-composed (Elgiloy) Wallgraft. The Wallgraft has polyethylene terephthalate on the outside of the stent, which is postulated to effect a better seal after the graft is punctured than those with the covering on the inside of the stent. This phenomenon may also be the result of the presence of a smaller potential space between the polytetrafluoroethylene dialysis graft and the polyethylene terephthalate–covered Wallgraft. Covered stents with the covering on the outside, as well as stents with small interstices between the struts of the stent, may be better suited for repeated puncturing. Theoretically, woven polyethylene terephthalate is more prone to infection than extruded polytetrafluoroethylene; however, we did not encounter any infection in our small group of patients. These factors will require further study in larger groups of patients.
Follow-up in our group of patients was quite short, with 3 months being the shortest and 11 months being the longest period of follow-up. None of the grafts thrombosed during this time, so thrombolysis was not performed in any of the patients. We attribute this fact to effective graft surveillance rather than the presence of a stent-graft, because an outflow lesion is more likely to cause graft thrombosis than any other lesion. Indeed, one patient had two angioplasty treatments of a venous anastomotic stricture. We have performed successful pharmacothrombolysis and mechanical thrombolysis in patients with conventional self-expanding stents without complication. However, in those patients we exercised particular caution, using the Arrow-Trerotola device (Arrow International, Reading, PA) because of the potential risk of the device snagging on the struts of the stent. We recommend the same caution be exercised for using the device in a covered stent. Other mechanical thrombolytic devices, such as the Angiolet rheolytic device (Possis, Minneapolis, MN), do not have this same potential for snagging.
We use a purse-string suture to close our puncture sites in patients who have undergone successful thrombolysis, because these patients are receiving anticoagulants. We used the same manner of closure in this study without complication. Because large access sheaths are used for the introduction of a Wallgraft, they could theoretically predispose to further pseudoaneurysm development. However, we believe that pseudoaneurysm development in dialysis grafts is multifactorial and is unlikely to be related to a single puncture. However, simple safeguards should be used to prevent pseudoaneurysm development, such as puncturing through a healthy region of skin and ensuring adequate hemostasis after sheath removal.
The Wallgraft device is substantially more expensive than polytetrafluoroethylene, and a case could be made that this method of treating graft pseudoaneurysms is not as cost-effective as surgery. However, when operating and recovery room costs, patient convenience, and the early return to hemodialysis are factored in, the disparity in actual cost is not as great. The financial implications of the two forms of treatment require further study.
Our limited experience with this small group of patients suggests that use of the Wallgraft is a viable option for treating a graft-threatening pseudoaneurysm. Puncturing the Wallgraft during dialysis access did not appear to cause any recurrence of the pseudoaneurysm in the medium term in this group, nor did it appear to affect the integrity of the Wallgraft. Because of the vital importance of maintaining every viable access in patients undergoing hemodialysis, prolonging the usefulness of an access using this therapeutic approach would appear to be worthwhile [7].
|
TopIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
 |
|
  N. R. Barshes, S. Annambhotla, C. Bechara, P. Kougias, T. T. Huynh, A. Dardik, M. B. Silva Jr, and P. H. Lin Endovascular Repair of Hemodialysis Graft-Related Pseudoaneurysm: An Alternative Treatment Strategy in Salvaging Failing Dialysis Access Vascular and Endovascular Surgery, June 1, 2008; 42(3): 228 - 234. [Abstract] [PDF]
|
|
|
|
 |
|
 H. E. Rodriguez, L. Leon, P. Schalch, N. Labropoulos, M. Borge, and P. G. Kalman Arteriovenous Access: Managing Common Problems Perspectives in Vascular Surgery and Endovascular Therapy, June 1, 2005; 17(2): 155 - 166. [Abstract] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
