the presence of an abdominal aortic aneurysm ( aaa ) in a patient with a functioning renal transplant poses a significant surgical challenge because it is important to avoid ischemic and reperfusion injury to the transplanted kidney .
conventional open repair of aaa in these patients requires ischemia - protecting procedures for transplanted kidney such as a temporary axillo - femoral bypass , aortoiliac shunt , aorto - femoral shunt , atrio - femoral bypass , femorofemoral bypass with extracorporeal circulation , topical cooling , and cold perfusion of the graft .
endovascular aaa repair ( evar ) avoids aortic cross clamping and can be an attractive option due to little or no impairment of renal arterial flow . here
the first patient was a 60-year - old man presenting with an asymptomatic , 6.0 cm expanding infrarenal aaa ( fig .
he underwent a renal transplantation 21 years prior to his current presentation due to renal failure secondary to diabetes and hypertension .
his renal function was marginal due to chronic rejection with creatinine and blood urea nitrogen ( bun ) values of around 4.0 mg / dl and 50 mg / dl , respectively .
his aaa was repaired with a zenith ( cook medical inc . , bloomington , in , usa ) bifurcated stent graft .
a 30 mm  117 mm zenith main body device was placed through the left common femoral artery with " preclose technique " using 7f proglide ( abbott vascular , redwood city , ca , usa ) .
an 18 mm  71 mm limb extender was used as the ipsilateral extension . a 24 mm  71 mm
a type ib endoleak arising from the right iliac artery was noted on the completion angiogram ( fig .
another 24 mm  54 mm limb extender was placed to overcome this type ib endoleak .
a total of 30 ml of visipaque ( iodixanol ) was used for this patient .
the patient 's renal function was slightly decreased after evar ( creatinine and bun of 4.1 - 4.4 mg / dl and 53 - 58 mg / dl , respectively ) .
the aggravation of chronic rejection led to hemodialysis 4 months after evar . over the following 12 months
the second patient was a 67-year - old woman presenting with asymptomatic 6.5 cm - sized infrarenal aaa .
nineteen years ago , she underwent a renal transplantation for renal failure secondary to diabetes and hypertension .
preoperative computed tomographyangiography ( cta ) revealed a heavily calcified , stenotic lesion in the left external iliac artery .
2 shows the maximal intensity projection view of the preoperative cta and the volume rendering view of the postoperative cta .
after the creation of the iliac conduit on the left iliac bifurcation using 10 mm dacron graft ( fig .
3a ) , her aaa was repaired with an zenith ( cook medical inc . ) bifurcated stent graft .
a 28  117 mm zenith main body device was placed through the iliac conduit ( fig .
two limb extenders of 14 mm  71 mm and 12 mm  54 mm were used as contralateral extension .
the guidewire was not passed during the cannulation of contralateral gate due to sharp angulation and heavy calcium on the right common iliac artery ( cia ) .
the guidewire could be passed after snaring the wire , which was inserted though left brachial artery ( fig .
a total of 120 ml of visipaque ( iodixanol ) was used for this patient .
several case series have shown evar is a promising alternative to open surgical treatment [ 3 - 6 ] .
we have described endovascular aortic aneurysm repair in 2 patients with transplant kidney and multiple comorbid medical conditions .
lacombe reported the open repair of aortoiliac aneurysm in 18 patients with kidney transplantation without mortality . during the open repair , however , aortic cross clamping was needed .
the arterial occlusion time between aortic clamping and revascularization of the transplant ranged from 25 to 50 minutes ( mean , 38 minutes ) .
the maximum increase of blood creatinine value occurred on the third postoperative day even in patients with normal transplant function .
comparisons between patients treated with open surgery versus evar were performed in terms of renal function . in the evar group ,
the pre- and postoperative creatinine ( cr ) was 1.69 and 1.73 mg / dl , respectively , ( p = 0.412 ) without any protective kidney allograft perfusion measures . in the open group , the pre- and postoperative cr was 1.45 and 1.37 mg / dl , respectively ( p = 0.055 ) . in 16% , no adjuvant allograft perfusion was provided . in the remainder
no differences in cr between evar and open techniques ( p = 0.13 ) were seen .
they concluded that evar without special allograft protection measures seems to be equally effective as open surgery with or without adjuvant kidney transplant perfusion . in our series , we performed evar without any allograft protection maneuver .
on preoperative planning for evar , special concern is where to put the main body of the device .
there are both advantages and disadvantages to stent - graft insertion through the transplant side .
scarring from previous transplant surgery often fixes the artery , prevents straightening of tortuous vessels , and thus may impede insertion of the delivery system .
also , it is crucial that the stent - graft length determinations be very accurate in order to avoid exclusion of the origin of the transplant artery by inadvertent coverage with stent - graft material . alternatively , insertion of the delivery system through the contralateral iliac system may be easier and safer . in our case
another concern is the cannulation of contralateral gate of the bifurcated device due to heavy calcium and acute angulation of iliac arteries .
if it is difficult to cannulate the contralateral gate , a brachial approach and snaring the wire is a possible option as in our case .
the preparation and draping of left arm is needed when difficulty of contralateral cannulation is expected .
another important concern is the possibility of embolization of the transplanted kidney or damage to the iliac artery .
even though all endovascular procedures carry the risks of embolization , special care is needed in the region of the transplant artery origin to prevent dissection during insertion of the guidewire or device .
if there is much mural thrombi in the iliac artery or aneurysmal sac , more gentle manipulation should be done . in our opinion
, evar is indicated only in patients with suitable anatomy of aneurysm for endovascular repair .
if the cia shows circumferential calcium with severe stenosis , extensive mural thrombus , or short working length for endovascular procedure , we recommend conventional open repair .
iliac access conduits are valuable tools to facilitate endovascular arterial access in clinical situations such as the presence of small and/or diseased ( calcified ) femoral and external iliac arteries and the need for introduction of a large - bore sheath or catheter size 22f .
standard surgical techniques are used to achieve retroperitoneal exposure of the cia via a relatively short oblique incision in the lower quadrant of the abdomen .
a 10-mm diameter dacron graft is the best conduit as it provides enough luminal space for introduction of all delivery systems .
the anastomosis is sewn end - to - side between the graft and the cia using a running suture technique . in the second patient ,
the left external iliac artery showed a heavily calcified , stenotic lesion with a diameter less than 5 mm .
we overcame this lesion with the creation of a left iliac conduit using 10 mm dacron graft .
another option is the internal endoconduit , which creates a controlled rupture of the iliac artery and facilitates remote femoral artery access .
the variety of available stent - grafts can be used in an off - label fashion to create an endoconduit . in summary ,
evar in patients with a renal transplant is a feasible option without impairing renal arterial flow .
 the repair of abdominal aortic aneurysm ( aaa ) in patients with functioning renal transplant is critical because it is important to avoid ischemic and reperfusion injury to the transplanted kidney . 
 endovascular aneurysm repair ( evar ) avoids aortic cross clamping and can prevent renal graft ischemia . here 
 we report the endovascular management and outcome of aaa in two renal transplant patients using a bifurcated aortic stent graft . 
 one patient underwent evar using a small amount of contrast ( 30 ml ) due to decreased renal function resulting from chronic rejection . 
 another patient had evar performed with iliac conduit because of the heavily calcified , stenotic lesion of external iliac artery . 
 evar in patients with a renal transplant is a feasible option without impairing renal arterial flow . 
INTRODUCTION
CASE REPORT
DISCUSSION