Successful use of lithoplasty for re-expansion of covered iliac stents with unilateral occlusion

Introduction

Vascular wall calcification impedes technical success and durability of catheter-based interventions for peripheral artery disease (PAD). Wall calcium is reported in up to 50% of PAD patients, ¹ especially those with advanced age, diabetes, and chronic kidney disease. ² Calcific burden within the arterial wall can lead to stent malapposition and/or under-expansion and eventually in-stent stenosis or occlusion. The traditional options to modify intravascular calcium includes percutaneous transluminal angioplasty (PTA) ³ and atherectomy ⁴ ; however, their outcomes are limited and may be associated with vascular complications.^4,5 In 2016, the U.S. Food and Drug Administration approved the use of Shockwave intravascular lithotripsy system (IVL; Shockwave Medical, Inc., Santa Clara, CA) for treatment of severely calcified PAD lesions. ⁶ The IVL generates sonic pressure waves that disrupt calcified lesions within the vessel walls while sparing surrounding tissue due to the difference in their densities.

Multiple studies have been conducted proving IVL safety and efficacy in PAD patients with severely calcified arterial segments.^3,7,8 However, the existing literature on IVL use in the treatment of stent under-expansion or in-stent restenosis due to calcification is sparse.^9,10 Specifically, most of the current reported cases of IVL use for in-stent restenosis are limited to the coronary artery territory where bare metal stents are the culprit platforms. Herein, we present a case where IVL was successfully used in the treatment of an under-expanded covered stents caused by extrinsic compression from the calcified atheromatous plaque of the aortoiliac artery. The calcified lesion led to the failure of the initial revascularization attempt. This case represents an additional application for this nascent technology.

Case report

The patient is a 55-year-old non-Hispanic White male who presented with severe bilateral lower extremity short-distance intermittent claudication (IC), more severe on the right side. His right foot was remarkable for rest pain and dependent rubor. By history, he had undergone a percutaneous aortoiliac endovascular intervention using kissing balloon expandable covered stents to treat aortoiliac stenosis with high calcific burden, and coral reef morphology. The patient was maintained on clopidogrel 75 mg once daily. The index procedure was performed for IC and within days of the intervention he developed rest pain in the right leg.

On examination, his right foot was ruborous with no ipsilateral femoral, popliteal, or pedal pluses. A pedal pulse was present on the left. The resting ankle-brachial indices (ABI) were 0.54 on the right and 0.95 on the left. The computed tomography angiography (CTA) revealed the right common iliac artery (CIA) stent compression with total occlusion of both the right common and external iliac (EIA) arteries (Figure 1). A report from the outside hospital revealed that the initially placed stent was 8 mm in diameter. Imaging following the procedure demonstrated a compressed vessel to less than 1 mm. The length of the occluded segment was 200 mm (123 mm previous stent length). The right common femoral artery was reconstituted via collaterals with normal 3-vessel runoff to the foot and ankle. His left aortoiliac system (CIA and EIA) was patent but there was severe compression of the left CIA stent.OPEN IN VIEWER

Bilateral femoral and left brachial vascular access was obtained using ultrasound guidance. A stiff angled guidewire was used to traverse the occluded right common iliac stent, and intravascular ultrasound (IVUS) was used to confirm positioning within the true lumen of the vessel before it was pre-dilated with a 5-mm non-compliant angioplasty balloon on 10 atm (Figure 2(A)). Next, the IVL system (Shockwave Medical, Inc., Santa Clara, CA) with a 6-mm balloon was introduced over a 0.014 guidewire (Figure 3). The patient was given unfractionated heparin to achieve activated clotting time above 250 s. The IVL balloon was inflated to 4 atm and 300 pulses were delivered. A completion IVUS demonstrated improved luminal diameter of the previously compressed stent. Similarly, 150 pulses with a 6-mm IVL device were delivered to the left CIA stent with improvement in diameter.OPEN IN VIEWER

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Figure 3.

Three-dimensional CT reconstruction of the pelvic area shows the right iliac artery before (a) and after (b) the intervention.

To re-expand the previously placed stents to the nominal diameter of the arterial segments, bilateral 7 x 57 mm balloon expandable (BE) covered stents (Express LD, Boston Scientific, Marlborough, MA) were placed in a kissing fashion in the distal aorta extending down to distal common iliac arteries. On the right, we extended down to the origin of the common femoral artery with 10 x 100 mm and 10 x 40 mm self-expanding bare metal stents (Epic, Boston Scientific, Marlborough, MA). Stents were post-dilated bilaterally to 7 mm with 10 atm. The previously extrinsically compressed under-expanded stent expanded fully and was well apposed to the artery. A completion angiogram and postilataion IVUS revealed a satisfactory result, with <10% residual stenosis without the evidence of dissection, embolization, or contrast extravasation (Figure 4). The patient was discharged home the next day after an unremarkable hospital.OPEN IN VIEWER

During the 4-week follow-up visit, the patient was doing well and reported complete resolution of his lower extremity pain and claudication. His ABI was 1.12 on the right and 1.03 on the left. The duplex ultrasound showed normal velocities throughout his common iliac artery stents, and a CTA scan demonstrated widely patent bilateral common and external iliac arteries. At 24 months of surveillance, ultrasound reveals his stents to be widely patent.

Discussion

The traditional endovascular techniques for the treatment of heavily calcified peripheral vessels include PTA and atherectomy (laser, orbital, or rotational). PTA alone usually provides suboptimal results in the treatment of severely calcified vessels. ¹¹ To date, atherectomy has been the most commonly used and demonstrates technical success but with multiple procedural complications, most notably peripheral embolization. However, several reports of patients with infrainguinal lesions including the DEFINITIVE Ca++ study demonstrated 2.2%–3.3% of distal embolic (DE) events following rotational, directional, and orbital atherectomies compared to zero DE events in IVL DISRUPT study.^12,4,13

IVL is a relatively new treatment for de novo, calcified, stenotic peripheral and coronary arteries.^8,14 This novel technology is based on lithotripsy, which began as a treatment modality for renal calculus. The technology works by fracturing the superficial and deep layers of dense calcium-based stones into small fragments that pass with urine. ¹⁵ In IVL, a saline-filled angioplasty balloon component is used to oppose the vessel wall, transmit energy, ¹⁶ and provide a harmless low-pressure dilatation of the vessel lumen following the plaque disruption. Two single-arm multi-center studies (DISRUPT PAD I–II)^7,17 and a third two-arm randomized clinical trial (DISRUPT PAD III)^3,8,18 reported data on the use of IVL in severely calcified peripheral arteries. The technical success was 100% with a final mean residual stenosis of 23%. Of note, no concomitant stents were placed. The study assessed the use of IVL prior to definitive treatment (drug-coated balloon (DCB) or stenting) compared to PTA in calcified femoropopliteal vessels. IVL was associated with lower maximal inflation pressure and flow-limiting dissection compared to PTA. The 1-year primary patency rate was significantly higher in the IVL arm (80.5% vs 68.0%).

In addition to our present study, two case reports have described the use of IVL in the treatment of inadequate peripheral stent expansion following endovascular management. A single case involved a covered stent used IVL 6 x 60 mm with the balloon inflated to 4 mm at 6 atm with 210 pulses delivered. ⁹ The previously placed stent was a covered 7 x 100 mm balloon expandable stent placed in the superficial femoral artery. A complete resolution of the patient’s rest pain and improvement in wound healing of toe ulceration was observed. Honton et al. ¹⁹ described a case where previously placed bilateral iliofemoral stents were complicated by severe right common iliac restenosis due to inadequate stent expansion from severe calcification. The stent type was not specified and presumed to be a bare metal. A total of 300 pulses were delivered using a 7 x 60 mm IVL catheter, with subsequent DCB angioplasty with a 7 × 80 mm balloon. The postoperative CTA showed significant improvement in the stent expansion and symptom resolution. Despite the technical success and outcomes of using IVL in covered in-stent restenosis, no test has been done to conclude whether the use of IVL for long periods of time will cause cavitation on the PTFE chemical structure.

We used IVL to achieve full expansion of occluded and extrinsically compressed covered stents. In our case, incomplete stent expansion resulted in failure of the index procedure for IC, resulting in rest pain when the previously open blood vessel occluded throughout. Alternative procedural options at the time of presentation included aortobifemoral or extra-anatomic revascularization. Severe calcium burden is associated with reduced primary and secondary patency for endovascular treatments in all vascular beds. In our review of the literature available at the time of the submission, this case represents the second published use of IVL for covered stent restenosis in PAD.

Conclusion

The current literature demonstrates the safety and efficacy of performing IVL in the treatment of peripheral complex calcified lesions. Our case is one of the few reported cases that describe IVL use to modify calcification-mediated stent compression, under-expansion, and occlusion. It is one of the two publications to describe IVL use for the rescue of occluded covered stents. IVL represents an effective tool in the management of vessel wall calcification both for primary and secondary interventions.