Introduction Distal protection devices are being utilized with increasing frequency in percutaneous treatment of atherosclerotic renal vascular disease. Early interventions utilized either a distal balloon occlusive device or filter wire to prevent particulate embolization from causing post-procedural decline in renal function. We describe a case in which a new protection device, the TriActiv system, was used to treat tandem aorto-ostial lesions of a solitary kidney with a dual arterial supply. Case Study A 73-year-old woman presented with a history of refractory hypertension. The patient was diagnosed with hypertension 10 years ago, but was noted to require escalating doses and greater than 3 blood pressure medications over the last 5 years. Medications on presentation included metoprolol tartrate 50 mg bid, nifedipine XL 90 mg qd, clonidine .1 mg tid, hydralazine 25 mg tid, lisinopril 10 mg daily, and simvastatin. Prior medical history was significant only for hyperlipidemia and previous 20 pack/year tobacco use. There was no history of coronary artery disease, peripheral vascular disease, or diabetes mellitus. Blood pressure was equal in both arms (205/105). There was no discrepancy in the pulses of the lower and upper extremities, no abdominal bruits, and no evidence of vasculitis or secondary vascular complications from the hypertension. Laboratory work-up revealed a normal thyroid function, potassium 3.6 mEq/L, bicarbonate 26 mEq/L, BUN of 26 mg/dl, and creatinine of 2.2 mg/dl. Renal insufficiency was apparently progressive with a Cr increasing from 1.4 mg/dl to 2.2 mg/dl, with no change, despite discontinuation of the ACE-inhibitor. She was diagnosed with Stage III kidney disease, with an estimated GFR of 30 cc. Noninvasive work-up revealed a 100% occluded left renal artery with a small 4.8 cm atrophic left kidney. The right kidney was normal sized, 10.6 cm, with a dual arterial supply from the aorta. The patient’s diagnostic renal angiography revealed an absent left renal artery, and an accessory cranial and main caudal renal arteries to the right side arising from closely separated ostia off of the aorta. Both arteries had greater than 95% ostial stenosis by visual estimate. The patient was subsequently scheduled for angioplasty and stenting. Bilateral arterial access was obtained with 7-Fr sheaths, and the patient was anticoagulated with bivalirudin (Angiomax, MDCO, Parsippany, New Jersey) bolus followed by continuous infusion. The cranial and caudal right renal arteries were sequentially engaged with 7-Fr short IM guide catheters (Guidant Corporation, Santa Clara, California). As the patient had a solitary kidney, and the risk of distal embolization of debris from the aorta was felt to be high, a no-touch technique was used in engaging both ostia, and a distal protection device was to be utilized for both arteries. An .035 J-wire extended slightly from the tip of both guide catheters during engagement to prevent the guide tip from abutting any atherosclerotic plaques. Subsequently, embolic protection ShieldWires from the TriActiv (Kensey Nash Corporation, Exton, Pennsylvania) Balloon Protected Flush Extraction System were placed across both lesions, and the .035 J-wires utilized in the no-touch technique were withdrawn. The distal protection balloons were then simultaneously inflated at 3 atm. The aorto-ostial lesion in the cranial right renal artery was crossed with a Herculink Transhepatic Biliary Stent (Guidant Corporation) 5.0 mm x 12.0 mm x 80 cm, and the aorto-ostial lesion of the caudal right renal was crossed with a Genesis Transhepatic Biliary Stent (Cordis, Miami Lakes, Florida) 5.0 mm x 12.0 mm x 75 cm stent. Using a kissing balloon technique, both stents were simultaneously deployed at 8 atm for 45 sec, respectively. Both stent balloons were quickly withdrawn and the FlushCath’s infused saline at 50 cc/min, followed by extraction at 125 cc/min in both right renal arteries. The distal protection balloons were then deflated after a mean occlusion time of 320 sec. Follow-up angiography revealed widely patent ostia, with no residual stenosis in either the cranial or caudal right renal artery. The patient was discharged the following day. Follow-up at 30 days revealed no major adverse clinical effect, with a reduction in creatinine to 1.3 and the discontinuation of 2 medications. Discussion Atherosclerotic renal artery stenosis is a well-known cause of secondary hypertension and chronic renal dysfunction. Recent evidence suggests that percutaneous intervention may result in a reduction of blood pressure, a need for multiple blood pressure medications, and delayed progression of renal insufficiency.1 While any part of the renal artery may be diseased, unlike fibromuscular dysplasia, the majority of atherosclerotic stenoses are located at the aorto-ostial junction, which often responds suboptimally to balloon angioplasty alone.2 Therefore, aorto-ostial stenting has recently been shown to be feasible, technically successful and resulting in improved clinical outcomes.3,4 Further complicating this renal intervention is the fact that dual (or, less commonly, multiple) renal arterial supplies are a normal anatomic variant present in 25–30% of people. A typical renal artery will split into anterior and posterior segmental arteries, with interlobar arteries supplying the upper, middle, and lower regions, and upper, posterior, and lower regions of the kidney, respectively. Dual unilateral renal arteries may supply either the anterior or inferior part of the kidney, or supply the superior inferior poles.5 While multiple arteries may preserve flow to sections of the kidney, unlike other organs, there are no significant collaterals between the various arteries once they branch off of the aorta. Intervening on a single aorto-ostial lesion causes the potential for plaque shifting and compromise of a neighboring artery. No previous reports have indicated the optimal way to approach single or tandem lesions in kidneys with dual arterial supplies. Despite the technical success rate and patency of stents, the benefits of the procedure are often limited by a 20–40% incidence of acute deterioration in renal function. The etiology of the acute injury to the kidney was believed to be due to possible reperfusion injury, contrast-induced nephropathy, or atheroembolism, but recent evidence indicates that significant atherosclerotic debris can be embolized distally into the renal parenchyma periprocedurally and can be primarily responsible for the increase in end-organ damage and poor clinical outcomes.6 Early observation from aortic atherosclerosis and aneurysm repair patients revealed a high incidence of cholesterol crystal embolization, causing obstruction in 55–900 µm vessels of the kidneys as well.7 Ex-vivo studies have revealed that angioplasty releases a significant number of atherosclerotic fragments, which can create vascular occlusion and induce local arteritis and parenchymal damage.8 In particular, stenting into a diseased aorta may place the patient at higher risk for renal infarction.9 In a landmark study, Holden, using the Angioguard device (Cordis Corp., Miami, Florida), revealed that while none of the patients without distal protection had improvement in renal function, 14 of 37 with distal protection had considerable improvement.10 Therefore, there has been an increasing use of various distal protection devices, which have been used with good success.11 However, because distal protection devices were not specifically designed for renal use, failure to achieve an optimal vascular seal have been noted with devices, such as the FilterWireEX (Boston Scientific, Natick, Massachusetts).12 Additionally, with various types of distal protection available, questions remain as to whether filter wires can be sufficiently deployed in short and tortuous renal arteries, and if they filter the sufficient size and proportion of particulate debris required for optimal results. Balloon distal protection devices are also often limited by the need for a deployment zone sufficiently distal to the target lesion, as well as the inability to expand beyond 5.5 mm vessel size. Trials, such as the Prospective Randomized Study Comparing Renal Artery Stenting With/Without Distal Protection (RESIST) and the Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL), are currently ongoing to assess the efficacy adjunctive medical and interventional techniques for this procedure. We describe a case report of a patient with atherosclerotic renal artery ostial stenosis of a solitary functional kidney with dual arterial supply. Although the kissing balloon technique has been previously described for renal artery stenosis, it was primarily for bifurcation lesions within a single renal artery and not tandem aorto-ostial lesions.13,14 We used a novel distal TriActiv distal protection device with simultaneous kissing balloon stenting of two aorto-ostial lesions within close proximity of each other. It was felt that, due to the presence of calcification and atherosclerosis of the aorta, total arterial occlusion with a distal balloon, followed by extraction, would be optimal for capture of embolized material. The primary limitation would have been inadequate distal occlusion, due to an undersized balloon, but stasis of contrast proximal to the balloon was confirmed prior to stenting. The TriActiv system is composed of three components: a 0.014´´ hollow-core wire with an elastomeric balloon (inflatable diameter, 3–6 mm) near the tip of the wire, a 5-Fr aspiration catheter, and a flush/extraction device. The wire is advanced beyond the lesion, and the balloon is subsequently inflated until antegrade blood and contrast flow ceases. The length of the deployment zone between the balloon and distal stent edge and the wire support during the intervention is similar to conventional filter wires. However, adequate distal protection would be limited if the renal artery bifurcated proximally. The intervention is then completed over the balloon-tipped wire, with subsequent flush extraction of any debris via a catheter introduced over the wire. The balloon is then deflated and follow-up angiography can be performed. Conclusion Kissing balloon stenting of tandem aorto-ostial lesions in a patient with a dual renal arterial supply is feasible. Additionally, the use of newer distal balloon occlusive devices, such as the TriActiv system, may be an effective alternative to previously studied devices.
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