Technical note: Improving orbital atherectomy efficacy for calcified nodules using a curved guide catheter

Introduction

A calcified nodule is a characteristic lesion that protrudes into the lumen, causing significant stenosis, particularly in coronary artery disease. ¹ In percutaneous coronary intervention (PCI), debulking devices have been developed to modify calcified lesions, including such nodules.

On the other hand, while calcified lesions are also prevalent in patients with peripheral artery disease (PAD) who undergo endovascular therapy (EVT), there has not been sufficient investigation specifically focused on calcified nodules. ² It has been reported that 29 % of patients who undergo EVT have calcified nodules as evaluated using intravascular ultrasound. ³ Subsequently, few studies have performed EVT for severely calcified lesions using debulking devices such as Jetstream, biopsy forceps, rotational atherectomy, and intravascular lithotripsy.^4–7 However, achieving an effective procedure is not always possible because lesions are substantially associated with poor outcomes after EVT.

Furthermore, due to the larger vessel size in peripheral arteries compared to coronary arteries, it was often difficult to direct debulking devices to the culprit lesion. This presents an additional pitfall in the EVT of calcified nodules.

In this case report, we present a patient with PAD experiencing leg claudication who had a severely calcified lesion protruding into the common femoral artery (CFA). We performed orbital atherectomy (OA) using an IM catheter to guide the target lesion and successfully treated the patient.

Case report

An 83-year-old man presented with PAD involving the bilateral femoral arteries (right common femoral artery and left common iliac artery). After undergoing endovascular therapy, his symptoms initially resolved, and he continued medical treatment for 2 years. In addition, the patient had lung cancer and interstitial pneumonia; however, he refused surgical treatment for these conditions and opted for continued medical therapy. Nevertheless, the PAD progressed in his right leg, resulting in claudication, which was graded Rutherford 3. The ankle–brachial index (ABI) decreased to 0.63 on the right side, and the leg angiography revealed 90 % stenosis in his right CFA with a severe calcified lesion, characterized by an eccentric calcified lesion (Figure 1). The patient also had severe stenosis of the left common iliac artery (CIA).

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Figure 1.

Angiogram before EVT. Leg angiogram before procedure (A) Right anterior oblique of right common femoral artery (CFA) (B) Anteroposterior view of right CFA (C) Left anterior oblique of right CFA.

Initially, we recommended physical training, but the symptoms still remained. Due to the high risk of complications associated with lung diseases (progressive cancer and interstitial pneumonia) and after a multidisciplinary discussion involving vascular surgery, we planned to perform percutaneous intervention. We initiated EVT on his left leg arteries: the left CIA was dilated with a conventional balloon, a drug-eluting stent was implanted using Misago 10/200 mm (Terumo, Tokyo, Japan), and the left CFA was dilated with a conventional balloon, followed by a 5/600 mm drug-eluting balloon (Ranger, Boston, MA, USA).

After completing EVT of the left leg arteries, we planned to treat the right CFA. A 6-Fr guiding sheath (Destination; Terumo, Tokyo, Japan) was retrospectively inserted into the left CFA and advanced into the right CFA. After crossing the right CFA with a 0.014-inch guidewire, we evaluated the lesion using optical coherence tomography (OCT; Abbott Vascular, Santa Clara, CA, USA), which revealed a calcified nodule in the right CFA (Figure 1). We advanced a 6-Fr IM catheter (Boston, MA, USA) to guide the culprit nodule and performed OA (Cardiovascular Systems, Inc., St Paul, MN, USA). The distance between the tip of the IM catheter and the OA was maintained at approximately 1.5–2.0 cm, which seemed to enable the IM catheter to contact the culprit lesion and OA most effectively (Figure 2). After 10 min of debulking, OCT confirmed successful modification of the nodule. Initially, we started with a guidewire in the superficial femoral artery (SFA); subsequently, the wire was advanced to the deep femoral artery to modify the wire bias. We repeated the procedure with OA guided by IM catheter for an additional 5 minutes. Contrast media was delivered during the procedure to detect any potential distal embolism or slow-flow phenomenon induced by debulking. No such unfavorable phenomenon was observed, and OCT confirmed significant debulking, with penetration near the center of the nodule at the culprit lesion (Figure 3). Subsequently, we inflated a peripheral cutting balloon (5.0/20 mm; Boston, MA, USA) and a drug-coated balloon using a IN.PACT. Admiral 5.0/400 mm (Medtronic, Dublin, Ireland) at the culprit lesion. The final angiogram and OCT revealed a significant reduction in the calcified nodule and an improvement in the culprit stenosis, resulting in a sufficient lumen area enlargement (Figure 3). The procedure successfully eliminated the patient’s claudication, with their ABI on the right side rising to 0.93. The patient remained asymptomatic at 6-month follow-up.

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Figure 2.

Position of devices during the procedure. Position of Destination, IM catheter, and orbital atherectomy during the procedure.

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Figure 3.

Series of OCT. The slice of (A)–(C) was traced in each session. OCT showing significant calcium debulking. OA, orbital atherectomy; DCB, drug coated balloon.

Discussion

The management of calcified lesions is a challenge in achieving favorable outcomes in EVT because peripheral artery substantially suffered from severe calcification.

Conventional ballooning or stent deployment for calcified nodules has difficulty achieving sufficient lumen enlargement due to stent under-expansion and carries a high risk of complications, such as perforation. Although several debulking devices have been reported to treat such lesions, their efficacy has not been established. Particularly in EVT, where the target vessel diameter is often large for the procedure, directing debulking devices to the culprit lesion can be challenging. In our case, the use of an IM catheter within the 6-Fr guiding sheath allowed us to modify the position of the OA to target the culprit nodule. During the procedure, controlling the position between the OA and IM catheters appears to be a key factor in managing the effectiveness of the IM catheter. A shorter distance between the IM catheter and OA might result in insufficient orbital motion, whereas a longer distance might hinder the direction derived from the curved guide catheter. We verified the association between the OA effect and device position. Although the distance should be considered in each procedure based on vessel size and characteristics, the distance between the guide catheter and OA may determine the effectiveness of the procedure.

Of note, the application of OA in EVT is off-label in Japan; however, the efficacy of this device has been repeatedly reported. Babaev et al. reported on 29 patients with PAD who underwent EVT with OA, experiencing symptom improvement without significant side effects. ⁸ It has also been reported that EVT with OA for severe calcification can achieve preferable outcomes without an increase in complications, including slow flow or no reflow phenomenon, compared to conventional ballooning. ⁹

To perform calcification debulking, several parameters are associated with an effective procedure, including wire bias and calcification thickness. ¹⁰ However, almost all variables are patient dependent and cannot be controlled by the procedure itself. Particularly in EVT for PAD with a large vessel size, it is sometimes difficult to control the debulking devices to touch the lesions. Although OA is classically reported to be effective in large vessels because of orbital motion itself, the maximum vessel size that could demonstrate efficacy has not been established.

From this point of view, the combination of OA and curved devices, such as IM catheters, could be effective in patients with PAD with large vessel sizes. In addition, the technique could be performed with alternative devices such as JETSTREAM and Rotablator. Additional examinations are required to establish the procedure.

Finally, the goal of the debulking procedure has not been established yet. Previous reports have evaluated the penetration of debulking devices, particularly in relation to their ability to reach near the center of the nodule. ¹¹ OCT findings from our case demonstrated deep penetration of the OA in the nodule near its center. The final OCT also revealed significant lumen enlargement in the culprit lesion.

This study had several limitations. First, OA is not yet approved for PAD in Japan. However, there is growing evidence supporting its use for debulking calcified lesions in patients with PAD, as demonstrated in studies conducted outside Japan,^8–10 and EVT with OA can be performed effectively without complications. Second, a distal embolism may be associated with a fatal prognosis after the procedure. Various distal protection methods can be considered; however, most techniques require additional interventions, such as distal puncture. Therefore, the application of distal protection should be carefully considered.

Conclusion

In this case report, we performed EVT with OA for calcified nodules in the right common femoral artery. Although controlling the OA to effectively engage the culprit lesion was challenging due to the large vessel size, the use of an IM catheter allowed precise direction of the OA toward the target lesion, enhancing the efficacy of the debulking device. Consequently, the combination of OA and the IM catheter achieved significant debulking of the calcified lesion without complications. This technique could potentially improve the management of calcified lesions, particularly in EVT procedures involving extensive calcification and large vessel diameters.