Percutaneous treatment of transplant renal artery stenosis: Techniques and results

Percutaneous Treatment of Transplant Renal Artery Stenosis: Techniques and Results John H. Rundback, MD, Addie Rizvi, and John Tomasula, MD

Transplant renal artery stenosis (TRAS) affects only a small percentage of renal allografts, but is a potential!y treatable cause of graft dysfunction and hypertension. Percutaneous transluminal angioplasty can be performed with technical and clinical success in most cases, and is the initial procedure of choice for TRAS. An understanding of the unique anatomy of the transplant kidney in the pelvis is critical to achieving success and avoiding complications. Because the transplant kidney represents the entire functional renal mass, careful attention to angiographic detail is crucial. This article outlines the techniques and results of transluminal angioplast~, for TRAS. Copyright 9 1999 by W.B. Saunders Company

ransplant renal artery stenosis (TRAS) occurs in 3% to 12.5% of transplant recipients, and is an increasingly recognized cause of potentially curable allograft dysfunction and refractory hypertension. 1.2 TRAS is more common in cadaveric donor kidneys and kidneys from pediatric donors younger than 5 years old) Several causative factors have been implicated, including mechanical damage to the donor or recipient artery due to clamping, cannulation or endarterectomy; turbulent anastamotic flow, and; immunologically mediated intimal proliferation. L2 Percutaneous transluminal renal angioplasty (PTRA) for TRAS was first described by Diamond et al in 1979. 4 Since that early report, PTRA has become well established as the principle therapeutic modality for patients with TRAS, and is performed with high rates of technical and clinical benefit and a low risk of graft loss. 3.59

T

Angioplasty Technique and Considerations Choice of Contrast Due to the frequent tortuosity of the transplant renal artery as well as overlapping iliac vessels, several projections may be necessary 1o fully evaluate the donor and recipient arteries for stenosis. Most angiographic examinations may be safely performed with nonionic low-osmolar contrast agents. When mild renal insufficiency is a concern, adequate digital subtraction angiographic images can be obtained using small volumes of dilute contrast; at the'Westchester Medical Center (WMC), the

From the Division of Vascular and Interventional Radiology, New York Medical College, Westchester Medical Center, Valhalla, NY. Address reprint requests to John H. Rundback, MD, Assistant Professor of Radiology and Surgery, Division of Vascular and Intewentional Radiology, New York Medical College, Westchester Medical Center, Valhalla, NY 10595. Copyright 9 1999 by W.B. Saunders Company 1089-2516/99/0202-0006S10.00/0

authors ohen use 50% strength contrast with 0.9% NaCI as the diluent. In these instances, prior knowledge of the type of anastamosis allows selective catheterization of the donor artery (either the hypogastric or external iliac artery) thereby minimizing the amount of contrast used. Although CO2 has been successfully used for transplant arteriograph); l~ it is the authors' experience that this does not provide adequate morphologic information for therapeutic planning. However, pelvic CO2 angiography may be useful for identifying the type and location of the transplant anastamosis before selective catheterization. Although there is recent experience with angiography of the nativerenal arteries using gadopentetate dimeglumine, ~ this has notbeen reported in patients with renal allografts.

Type of Anastamosis The transplant renal artery may be anastamosed to either the external iliac artery in an end-to-side fashion, or to the ligated h)'pogastric artery as an end-to-end connection. Generall>; renal arteries with an end-to-side anastamosis have a smoothly sloping cephalad course, and are therefore best approached from an ipsilateral femoral access. Because the anastamotic site is positioned on the lateral or anterolateral wall of the external iliac artery, arteries with an end-to-side anastamosis are best visualized in an anteroposterior or slight contralateral anterior oblique projection. In contrast, allografts with an end-to-end anastamosis to the hypogastric artery have a downward course from the common iliac arter); and are more easily catheterized from a contralateral femoral access site (Fig 1). In such cases, the use of a crossover sheath allows better catheter control for selective angiography and subsequent PTRA. Both oblique views are often necessary for full characterization of the transplant renal arter); with the contralateral anterior oblique showing the iliac bifurcation and hypogastric artery segment and the ipsilateral anterior oblique showing the length of the transplant renal artery. Caudal or cephalad angulation is often necessary to depict stenoses near or within segmental renal arterial branches.

Angiographic Appearance Stenosis of the transplant renal artery may be due to vessel kin.k._ing, rejection, or intrinsic narrowing. Kinking occurs more commonly when the .kidney is anastamosed to the hypogastric after); and the resulting narrm~dng is seen at or just beyond the anastamosis. Angiographicall>; the inferior aspect of the artery is smooth, while the superior portion of the artery is buckled and impinges on the vascular lumen. Focal diminished contrast density may be seen at the site of narrowing due to luminal compression, and rapid filming may show delayed transit of contrast past the stenosis. Allograft rejection is

Techniques in Vascular and Interventional Radiology, Vol 2, No 2 (June), 1999: pp 91-97

91

length wire (Rosen wire, Cook, Inc) is then inserted into the renal artery for subsequent angioplasty. Placing curves in the exchange wire to match the anatomical course of the catheterized renal artery can minimize wire buckling during catheter exchanges. ! Balloon size is selected to match the measured diameter of the renal artery in a normal segment proximal to the stenosis or distal to any poststenotic dilatation. The shortest possible balloon should be used to prevent injury to the adjacent normal vessel. Not uncommonly, stenoses are fibrous and therefore resistant to balloon inflation. It is advisable to use an angioplasty balloon with a relatively high-rated burst pressure. Newer balloons composed of coextruded polymers allow for inflation pressures up to 15 atm and are generally sufficient to attain full balloon dilatation. In such cases, a mechanical inflation device may be necessary to achieve complete expansion of the balloon, although occasionally complete dilatation

Fig 1. The p~referred approach to treatment of TRAS in an allograft with an end-to-end anastamosis is from the contralateral femoral access (A). This provides a smooth, tensionfree course across the hypogastric origin. In contrast, an ipsilateral femoral approach (B) results in a sharp curve into the donor hypogastric artery. Radial pressure exerted by the wire at this point (arrows) may "tack up" and mask a postangioplasty dissection (see Figure 6 and text).

manifested by multiple areas of segmental branch vessel narrowing, abrupt vessel cutoff, and a diminished or patchy nephrogram. Such lesions are generally not amenable to PTRA. Intrinsic arterial stenosis is usually focal, concentric, and somewhat irregular in angiographic appearance (Fig 2). Poststenotic dilatation is evident in more long-standing lesions. With severe narrowing, there may be underfilling of the intrarenal branches distal to the stenosis. A peak systolic trans-stenotic gradient of ->20 mm Hg is considered to be indicative of a hemodynamically significant obstruction, although lesser gradients may be important during episodes of coexisting rejection.

PTRA Technique All procedures are performed using a femoral sheath. Before crossing the stenosis, patients are systemically anticoagulated with 2,000 to 5,000 U of heparin sulfate, and 100 to 200 lag boluses of intra-arterial nitroglycerin are administered into the renal artery to prevent wire or catheter-related spasm and thrombosis. The lesion is traversed with a floppy-tip guidewire (Bentson wire, Cook Inc, Bloomington, IN), or Tad II wire (Mallinckrodt Medical Inc, St Louis, MO). Placing a slight curve on the tip of the wire will often facilitate lesion passage. Occasionall); hydrophilic-type guidewires will be necessary to cross a tight stenosis. However, these should be used with extreme caution due to an increased tendency of arterial dissection. The diagnostic catheter is then advanced over the wire into the distal main transplant renal artery or a proximal segmental branch, and intraluminal positioning is confirmed by the injection of a small amount of contrast. A stiff exchange

92

Fig 2. There is an irregular, concentric RAS in a right pelvic transplant kidney (A). Note that this end-to-end anastamotic lesion is approached from the contralateral groin. There is wide patency after PTRA (B).

RUNDBACK, RIZVI,AND TOMASULA

will still be impossible despite these measures (Fig 3). Centerences in implantation technique between different endoprostheing the balloon on the stenosis prevents movement during ses. The most commonly used balloon-expandable stent is the inflation and maximizes the radial force exerted on the lesion. Palmaz stent (Cordis Inc, Warren, NJ). This is either preloaded Similarl}; the balloon catheter should be stabilized at the skin or hand-crimped onto an appropriately sized balloon, and site, and inflation should be performed gradually to avoid advanced through a 6 to 7F sheath or 8F guiding catheter slippage and potential plaque fragmentation or dissection. positioned across the lesion (Fig 5). Due to the tortuosity of the Balloon inflation is performed using dilute contrast. The transplant artery, attempting to advance the stent without a balloon is left inflated for 15 to 30 seconds, and then carefully sheath or guide should be avoided as this may result in deflated. Some operators prefer to perform a second dilatation, dislodgment of the stent and risk vessel injury. After positionalthough this has not been proven to improve technical ing, the sheath or guide is retracted, and angiography is outcomes. After deflation, the angioplasty balloon is carefully performed to confirm an adequate stent location. The stent is removed. Wire access across the lesion is maintained for a then deployed by balloon inflation using saline or dilute completion arteriogram performed through the sheath sidecontrast. Palmaz stents are available in lengths as short as 10 to arm. Should this provide insufficient evaluation of the treated 20 mm, and the shortest possible stent should be chosen (Fig site, a muhisidehole catheter can be positioned across the 5). treated site for improved opacification. The Wallstent (Boston Scientifics Vascular, Watertown, MA) Stenoses extending to or involving the renal arterial bifurcais the most frequently used self-expandable stent. When using tion may be treated using a "kissing balloon" technique (Fig 4). a Wallstent, the constrained stent and introducer are advanced Using angiographic roadmapping or fluoroscopic guidance, across the stenosis and deployed by retraction of the outer both segmental branch~es are crossed with a short-taper floppycatheter membrane while stabilizing the inner stent pusher. If tipped 0.018" or 0.0114" guidewire. While the stiff (mandrel necessary, the stent can be reconstrained and repositioned after supported) portion of the wires need to be positioned across release of up to 80% of its length. Alternatively, repositioning the stenosis, is it important that the wire tips not extend too far can be performed by pulling back on the entire delivery system into the renal arterial tree, as cortical penetration with a afterp.arfial stent deployment. Foreshortening and imprecise resulting perinephric hematoma may occur. Two low-profile 9 : positioningof the leading edge of the stent must be taken into peripheral or coronary balloons are then simultaneously posi! account before full release frOm the catheter. The stent selected tioned and inflated. Balloon size should correspond to the should be 10% to 20% larger than the diameter of the target measured diameter of the segmental vessel being dilated. After vessel. Additionally, postimplantation balloon inflation is recPTRA, wire position across both branches should be mainommended to assure that the stent struts are completely tained during completion arteriography. embedded in the wall of the vessel. Suitable Wallstents are available in 20 mm lengths and are 7 to 8 mm in diameter.

Stenting There have been several recent reports describing the use of metallic stents for allograft renal artery stenosis, 12-15predominantly for recurrent stenosis after previous PTRA. However, stents are also potentially valuable for elastic lesions, arterial kinking, and for the management of flow-limiting dissections occurring after angioplasty. Both balloon-expandable and selfexpandable stents have been used, with considerable differ-

Complications The most common complications of transplant PTRA are puncture-site related (eg, hematoma, pseudoaneurysm). Potential complications specific to PTRA include contrast-induced nephrotoxicity, vessel rupture, occlusive dissection, thromboembolism, and distal spasm. The liberal use of intra-arterial or

Y

M

B Fig 3. Fibrous lesion resistant to balloon dilatation. There is a focal high-grade postanastamotic TRAS in a kidney with an end-to-side anastamosis to the external lilac artery (A). Despite Inflation up to 15 atm, the waist on the balloon at the site of the stenosis could not be eliminated (B). Residual stenosis with a non-flow-limiting dissection is noted at the site of PTRA (C). However, there was improved flow to the kidney.

PERCUTANEOUS TREATMENT OF TRAS

93

el,,

A Z t

Fig 4. "Kissing-balloon" renal angioplasty. Transplant RAS extending into both segmental branches (A). After positioning 0.018" guidewires in each branch, "kissing-balloon" angioplasty is performed using two low-profile balloons simultaneously inflated (B). Tibial or coronary type balloons are suitable for this purpose. Completion angiogram after PTRA shows an excellent result in both segmental branches and in the main renal artery (c).

intravenous heparin sulfate reduces the risk of procedurerelated thrombosis, and the administration of small boluses (100 to 200 lag) of nitroglycerin into the renal arterial tree helps prevent wire-induced spasm. Avoiding excessive wire movement or advancement into the smaller segmental branches during catheter exchanges may also prevent spasm. Arterial rupture is a rare but serious complication. In such instances, the angioplasty balloon or a latex occlusion balloon should be inflated across the s i t e o f extravasation. Due to the limited warm ischemia time of renal allografts (approximately 30 minutes viability), vascular repair by surgical exploration, or more recently stent-graft placement must be undertaken emergently. The development of an occlusive dissection after PTRA is also uncommon, but can usually be recognized immediately and treated by endovascular stent placement. However, the authors have encountered one case with an end-to-end anasta-

94

mosis in which the completion arteriogram (with a wire in place) did not immediately show a dissection of the superior aspect of the renal artery origin. In this case, the artery was approached from the ipsilateral groin, and the wire presumably "tented up" the dissection flap (Fig 1, Fig 6); upon removal of the wire the intimal flap moved downward and obstructed the arterial lumen. For this reason, the authors now approach all allografts with an end-to-end anastamosis from a contralateral femoral access.

Results Contemporary results of angioplasty for TRA5 are summarized in Table 1. Overall, technical success is achieved in 84% of patients, with major complications in 12%. The cumulative restenosis rate is 20%. However, despite this relatively high

RUNDBACK, RIZVl, AND TOMASULA

r

&

r

!, I

9

t

[ |

t

|

t

I I

t E !

I !

t

Fig 5. Transplant renal artery stenting. Selective angiography shows a short, tight stenosis of the distal transplant renal artery (A). Lesions of this type are often due to clamp injury and/or traumatic cannulation. After PTRA, there is approximately 60% residual stenosis. Because the balloon could be completely inflated, this represents either elastic recoil or a focal dissection (B). A 15-ram-long balloon premounted coronary Palmaz stent (Cordis Inc, Warren, NJ) is positioned across the residual stenosis and deployed by gentle balloon inflation (C). A final angiogram shows wide patency at the stented site (D). The slight step-off in caliber compared with the adjacent artery is due to a restriction in the maximal inflatable diameter of this stent to 5 mm.

incidence of restenosis, there is only a 22% rate of graft loss during nearly 3-year followTup, attesting to the durability of repeat interventions. Furthermore, nearly all allograft failure is related to superceding events, most notably acute or chronic rejection. When PTRA is successful, graft loss is uncommon. 16 At WMC, the authors have treated TRAS in 23 of 742 (3.1%) transplant recipients over the past 7 years. Technical success, defined as <30% residual stenosis after PTRA, was achieved in 84% of patients. There were three major complications, including two early graft losses due to occlusive dissection and

PERCUTANEOUSTREATMENTOF TRAS

thrombosis, respectivel); and one lower pole thrombosis that was successfully salvaged with catheter-directed thrombolysis. Functional benefit was noted in 84% of patients, including more than half who had a greater than 20% reduction in creatinine after PTRA. The mean serum creatinine before intervention was 3.2 mg/dL, which was lowered to a mean of 2.4 mg/dL in the entire group at 6-month follow-up. The 1-year graft survival was 67%. Excluding technical failures, the mean time to graft loss in patients failing PTRA was 21/2 months; in 3 of these 5 patients, graft loss occurred secondatT

95

9

J

i

L. . . . . .

,q

0

Fig 6. Post-PTRA arterial occlusion due to an unrecognized dissection, lilac arteriogram reveals a focal anastamotic stenosis (arrow) just beyond the origin of the hypogastric artery (A). The lesion was treated from an ipsilateral femoral access (B). Note the sharp curve on the wire and balloon across the stenosis. Angiography after PTRA appears to show a good result. However, careful inspection reveals a dissection flap in the upper portion of the artery (curved arrow) that is held due place by radial force exerted by the guidewire (Fig 1) (C). Angiogram performed after wire removal shows complete occlusion of the transplant renal artery due to the dissection (arrow) (D). The patient subsequently was sent for emergent surgical repair but died on the operating table.

96

RUNDBACK, RIZVI, AND TOMASULA

TABLE 1. Contemporary Results of PTRA for AIIograft RAS Clinical Benefit First Author, Year

N (Patients/ PTAs)

Technical Success (%)

Follow-Up (mo)

Hypertension (%)

Renal Function

76 100

26% improved 60% stable 67%]1

Bover (1992) 9 Thomas (1992) 8

27127 15/14

93 93

6 34

Fauchald (1992)~'

25/33

88*

24

64w

Matalon (1992) 6

18/24

581"

12

63w

Lo (t996) s Sankari (1996) 3 Rundback (1999):1:

14118 16/16 23/28

94 75 78

24 45 6

67 75 100

1371160

84

-20

78

7 series

50% improved 39% stable 69% 56% improved~ 28% stable 79%

Graft Survival (mo)

Restenosis (%)

Major Oxs (%)

79% at 34

12 20

7 21

88% at 24 80% at 60 67% at 23

24

12

14

11

100% at 24 75% at 45 67% at 12

33 25 17

11 19 12

78% at 34

20

12

Abbreviation: Cxs, complications. *<50% residual stenosis after PTRA. 1<20% residual stenosis after PTRA. :[:Current series. w decrease in mean blood pressure. 11>15% reduction in serum creatinine. 82 or improved renal function.

to associated acute rejection. Of note, in all cases of PTRA restenosis, restored patency.was achievable by either repeat PTRA or stent placement (4 of 5) or surgical revascularization (1 of 5).

Conclusion Transplant PTRA can be performed with high initial technical success and improves hypertension and allograft function in most patients. Despite technical complexities and frequent restenosis, rigorous surveillance and repeat intervention can prevent graft loss in most cases. These results justify the use of PTRA as the initial therapeutic option for patients with allograft dysfunction or hypertension caused by TRAS.

References 1. Fervenza FC, Lafayette RA, AIfrey EJ, Petersen J: Renal artery stenosis in kidney transplants. Am J Kid Dis 31:142-148, 1998 2. Wong W, Fynn SP, Higgins RM, et al: Transplant renal artery stenosis in 77 patients-does it have an immunological cause? Transplantation 61:215-219, 1996 3. Sankari BR, Geisinger M, Zelch M, et al: Post-transplant renal artery stenosis: Impact of therapy on long-term kidney function and blood pressure control. J Uro1155:1860-1864, 1996 4. Diamond NG, Casarella W J, Hardy MA, Appel GB. Dilatation of critical transplant renal artery stenosis by percutaneous transluminal angioplasty. Am J Roentgenol 133:1167-1169, 1979 5. Lo CY, Cheng IKP, Tso WK, Mak KO: Percutaneous transluminal angioplasty for transplant renal artery stenosis. Transpl Proceed 28:1468-1469, 1996

PERCUTANEOUS TREATMENT OF TRAS

6. Matalo a TAS, Thompson MJ, Patel SK, et al: Percutaneous translumin.41 angioplasty for transplant renal artery stenosis. J Vasc Interv R,4diol3:55-58, 1992 7. Fauchald P, Vatne K, Paulsen D, et al: Long-term clinical results of percutaneous transluminal angioplasty in transplant renal artery stenosis. Nephrol Dial Transplant 7:256-259, 1992 8. Thomas CP, Riad H, Johnson BF, Cumberland DC: Percutaneous transluminal angioplasty in transplant renal arterial stenoses: A long-term follow-up. Transplant Int 5:129-132, 1992 9. Bover J, Montana J, Castelao AM, et al: Percutaneous transluminal angioplasty for treatment of allograft renal artery stenosis. Transplant Proceed 24:94-95, 1992 10. Kuo PC, Petersen J, Semba C, et at: CO2 angiography-a technique for vascular imaging in renal allograft dysfunction. Transplantation 122:652-654, 1996 11. Spinosa DJ, Matsumoto AH, Angle JF, Hagspiel KD: Use of gadopentetate dimeglumine as a contrast agent for percutaneous transluminal renal angioplasty and stent placement. Kidney Int 131:503-507, 1998 12. Sierre SD, Raynaud AC, Thierry C, et al: Treatment of recurrent transplant renal artery stenosis with metallic stents. J Vasc Interv Radiol 9:639-644, 1998 13. Nicita G, Villari D, Marzocco M, et al: Endoluminal stent placement after percutaneous transluminal angioplasty in the treatment of post-transplant renal artery stenosis. J Urol 159:34-37, 1998 14. Wai-Han Chan H, Ho YW, Chart CM, et al: Treatment of anastamotic ostial allograft and renal artery stenosis with the Palmaz stent. Transplantation 59:436-439, 1995 15. Newman-Sanders APG, Gedroyc WG, A1-Kutoubi MA, et al: The use of expandable metal stents in transplant renal artery stenosis. Clin Radi0150:245-250, 1995 16. McMullin ND, Reidy JF, Koffman CG, et al: The management of renal transplant artery stenosis in children by percutaneous transluminal angioplasty. Transplantation 53:559-563, 1992

97