Renal Angioplasty Under Protection of the PercuSurge GuardWire Plus System

Renal artery stenosis may occur in combination with hypertension and renal function impairment. Renal artery revascularization with angioplasty may facilitate hypertension control and preserve renal function.1,2 However, distal embolization with cholesterol embolization may lead to deterioration in renal function after the procedure. Distal protection may be helpful in preventing microembolization during the procedure. We report a case of successful renal artery angioplasty using the PercuSurge GuardWire Plus system (Medtronic USA, Inc., Minneapolis, Minnesota) as a distal protective device. Case Report. A 74-year-old gentleman was referred from outside the hospital for revascularization of a right renal artery atherosclerotic stenosis due to mild renal function impairment and hypertension requiring multiple antihypertensive drugs. He had a history of symptomatic sick sinus syndrome with a permanent pacemaker implanted. He had long-standing hypertension for decades, which required 4 hypertensive drugs for control. He also had ischemic heart disease with history of coronary angioplasty. His creatinine was around 160 mmol/L on referral. After informed and written consent, renal artery angioplasty and stenting were arranged. The patient had been on aspirin 160 mg daily and clopidogrel was given at 75 mg daily after a loading dose of 300 mg two days before the procedure. A 7 French (Fr) arterial sheath was placed through the right femoral artery for vascular access. The tortuous abdominal aorta rendered the usual renal curve guiding catheter unable to engage the right renal artery coaxially. A 7 Fr, coronary JR 3.5 guiding catheter (Cordis Corporation, Miami Lakes, Florida) was used. On angiogram, a 92% eccentric stenosis was located at the proximal right renal artery. The reference vessel diameter was 4.9 mm with a lesion length of 9.2 mm. A total of 6,000 units of unfractionated heparin were given intravenously and the first activated clotting time (ACT) 10 minutes later was 329 seconds. The GuardWire was initially used to cross the lesion. However, it failed to cross the lesion after repeated negotiations. The lesion was then successfully crossed with a 0.014´´ BMW wire (Guidant Corporation, Temecula, California). With the BMW wire in situ, the GuardWire was then able to successfully cross the lesion using the parallel wire technique. The BMW wire was then removed. The elastomeric balloon near the tip of the wire was then inflated to 6 mmHg with complete occlusion of the flow as confirmed by injection of diluted contrast. Through the GuardWire, a 4.0 x 15 mm U-Pass coronary balloon (Cordis Corporation) was passed to the lesion and inflated at 6 atm. This was followed by deployment of a 5.0 x 18 mm Bx Velocity stent (Cordis Corporation) at 15 atm. The Export aspiration catheter was advanced over the GuardWire until it lay just proximal to the occlusion balloon. Aspiration was then performed twice using a 20 cc syringe. The occlusion balloon was deflated to restore antegrade flow, after an occlusion time of 5 minutes and 16 seconds. Visible particles and debris were retrieved from the aspirate. The final residual diameter was 2%. The patient was given aspirin indefinitely with 4 weeks of clopidogrel at 75 mg daily. At 30-day follow-up, there was no major adverse clinical event. His blood pressure was well controlled with similar medications and his creatinine level was similar to his pre-procedure level without any deterioration. Discussion. Renal artery stenosis is commonly due to atherosclerosis or fibromuscular dysplasia, with atherosclerosis accounting for over 90% of cases. Atherosclerotic renal artery stenosis was associated with coronary and peripheral vascular disease, diabetes and hypertension.3 It is a progressive disease; without treatment, progressive stenosis may develop in more than half of the patients.4–6 Percutaneous intervention with balloon angioplasty with or without stenting may be indicated in patients with uncontrolled hypertension or renal function insufficiency. It is successful in 82–100% of patients.1 Due to the intrinsic mechanism of angioplasty, which involves compression and fissuring of atherosclerotic plaques, dislodgement of atherosclerotic materials during the procedure causing distal microembolization is an inevitable phenomenon. Indeed, renal function impairment after renal angioplasty occurs and may be related to cholesterol embolization. Therefore, distal protection during the procedure may prevent distal embolization and improve long-term outcomes. Distal protection may be accomplished through a distal occlusive balloon system or filters. Henry et al. showed that the distal occlusive system is safe and feasible during percutaneous renal interventions to protect against atheroembolism.7 However, distal embolization may occur during a difficult guiding catheter engagement and such embolization cannot be protected using the current distal protection systems. The best way to prevent distal embolization in this regard is an atraumatic guiding catheter entry. The PercuSurge GuardWire Plus system is composed of three components: 1) an inflation/deflation kit; 2) a 0.014´´ hollow-core GuardWire with an elastomeric balloon (inflatable diameter, 3–6 mm) near the tip of the wire; and 3) a 5 Fr aspiration (Export) catheter. During intervention, the GuardWire is first advanced beyond the lesion and the occlusive balloon is then inflated until the antegrade flow of contrast is blocked. Intervention with balloon and stent(s) is then performed using the GuardWire for support, followed by aspiration of debris by the aspiration catheter at the end of the procedure before the occlusive balloon is released. The GuardWire, when compared with conventional guidewires, is less controllable in terms of torque transmission and pushability. It may fail to cross complex or tight lesions, as happened in this case. The parallel wire technique has been found to be very useful in this situation. Despite its hollow-core characteristics, the wire provides adequate support for the renal angioplasty procedure once the wire has crossed the lesion. The 5 Fr Export catheter tracked through the 90° angle of the renal artery take-off and the deployed stent without difficulty. The problem with the occlusive mechanism, i.e., temporary cessation of blood flow during the procedure in the range of a few minutes, is seldom clinically significant during renal angioplasty when compared to angioplasty of other organ systems, like coronary and carotid angioplasty, which are much more sensitive to ischemia. Florack et al. found that kidney damage is predictably reversible when warm ischemic time is less than 30 minutes.8 Using the current GuardWire system, occlusion of flow for more than 10 minutes would be unusual; hence, device-induced ischemia due to the occlusion of flow is not clinically significant. Although temporary ischemia is not a major issue, the GuardWire system may not be suitable for all patients with renal artery stenosis. Since the inflatable range of the occlusive balloon is only up to 6 mmHg, it may not provide complete occlusion in renal arteries larger than approximately 5.5 mm in diameter. Moreover, the main renal artery needs to have adequate length between the lesion and the distal branch-off point to allow placement of the occlusive balloon and stent(s). For an ostial lesion that is able to be covered by a short 12 mm renal stent, the minimal length needed is probably around 25–30 mm in order to allow adequate length of the wire for support and to accommodate the balloon catheter tip. The GuardWire, and the filters as well, may not be suitable for short segment main renal artery stenosis. Whether the use of distal protection devices during renal artery intervention would lead to better long-term clinical outcomes requires further large-scale randomized trials. Our current experience indicates that the GuardWire system is safe and feasible in renal angioplasty.

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